is astronomy applied to the various extraterrestrial sources of radiation, especially at night. It is also conducted above the Earth's atmosphere and at locations away from the Earth, by satellites and space probes, as a part of explorational (or exploratory) radiation astronomy.
This image is a composite of several types of radiation astronomy: radio, infrared, visual, ultraviolet, soft and hard X-ray. Credit: NASA.
Seeing the Sun
and feeling the warmth of its rays is probably a student's first encounter with an astronomical radiation source. This will happen from a very early age, but a first understanding of the concepts of radiation may occur at a secondary educational level.
Radiation is all around us on top of the Earth's crust, regolith, and soil, where we live. The study of radiation, including radiation astronomy, usually intensifies at the university undergraduate level.
"[P]referential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon".
"For quenched galaxies, the Hα absorption trough is deep and can be traced through the nucleus and along the major axis. It extends to a radius at or beyond 2 Rd
is the galaxy disk scale length] in all but three cases. This makes it possible to determine a velocity width from the optical spectrum as is done for emission line flux, with appropriate corrections between stellar and gas velocities (see discussion in Paper I, also Neistein, Maoz, Rix, & Tonry, 1999). In the few cases where a velocity width can also be measured from the H I data, it is found to be in good agreement with that taken from the Hα absorption line flux."
Phase shift induced by free-streaming neutrinos and other light relics in the spectrum of baryon acoustic oscillations. Credit: Daniel Baumann, Florian Beutler, Raphael Flauger, Daniel Green, Anže Slosar, Mariana Vargas-Magaña, Benjamin Wallisch & Christophe Yèche.
"A pattern caused by sound waves in the early universe — known as baryon acoustic oscillations — should be distorted by the [early] neutrinos. Those sound waves spread outward through the universe like circular ripples on a pond, compressing matter into denser pockets. Eventually, that process resulted in galaxies having a tendency to cluster in rings across the sky [...]."
"Using data from the Baryon Oscillation Spectroscopic Survey, or BOSS, [to study] the circular patterns of galaxies [produced] evidence that the [early] neutrinos were, in fact, pulling matter around from the inner side of the ring band toward the outer side."
"A complementary and more robust probe [of the cosmic neutrino background] is provided by a distinct shift in the temporal phase of sound waves in the primordial plasma that is produced by fluctuations in the neutrino density."
"The effect of neutrinos on perturbations in the primordial plasma has been shown to be a more robust probe of the CνB4
. Neutrinos travel near the speed of light in the early Universe, significantly faster than sound waves in the hot plasma of photons and baryons, and can therefore propagate information ahead of the sound horizon of the plasma. The gravitational influence of this supersonic propagation induces a shift in the phase of the acoustic oscillations that cannot be mimicked by other properties of the plasma4,5
. This phase shift has recently been detected in the CMB5,6
, adding to the robustness of the cosmological evidence for the CνB."
"After recombination, photons decoupled from baryons and the sound waves lost their pressure support. The sudden halt to the propagation of these density waves leaves an overdensity of baryons at the scale of the acoustic horizon at recombination. Subsequent gravitational evolution transfers this overdensity to the matter distribution. The power spectrum of galaxies inherits this feature in the form of baryon acoustic oscillations (BAOs). It was recently pointed out that the BAO spectrum should not only exhibit the same phase shift from the supersonic propagation of neutrinos, but that this shift should also be robust to nonlinear gravitational evolution in the late Universe7
"A key property of neutrinos is that they do not behave as a fluid, but as a collection of ultra-relativistic free-streaming particles. As a consequence, neutrinos travel at the speed of light c while the sound waves in a relativistic fluid, like the photon–baryon fluid, travel at cs
≈ c/√3. The supersonic propagation speed of neutrino perturbations creates a characteristic phase shift [see image on the right (a)] in the sound waves of the primordial plasma. A useful way to understand the effect is to consider the evolution of a single initial overdensity11,12
. (For adiabatic fluctuations, the primordial density field is a superposition of such point-like overdensities.) The overdensities of photons, baryons and neutrinos will spread out as spherical shells, while the dark matter perturbation does not move much and will be left behind at the centre. Because the neutrinos travel faster than all other perturbations, they induce metric perturbations ahead of the sound horizon rs
of the acoustic waves of the photon–baryon fluid."
Image on the right part (a) shows the template "of the phase shift f(k) (blue) [...[, with the fitting function [...] shown as the red curve. The template was obtained numerically in ref.8
by sampling the phase shift in 100 different cosmologies with varying free-streaming radiation density. The blue bands indicate the 1σ and 2σ contours in these measurements."
In the image on the right part (b), "Linear BAO spectrum O(k) [is] a function of the amplitude of the phase shift β."
Active galactic nuclei
The image contains a series of radio images at successive epochs using the VLBA of the jet in the broad-line radio galaxy 3C 111. Credit: M. Kadler, E. Ros, M. Perucho, Y. Y. Kovalev, D. C. Homan, I. Agudo, K. I. Kellermann, M. F. Aller, H. D. Aller, M. L. Lister, and J. A. Zensus.
There is "a correlation between the arrival directions of cosmic rays with energy above 6 x 1019
electron volts and the positions of active galactic nuclei (AGN) lying within ~75 megaparsecs."
Some low energy cosmic rays originate or are associated with solar flares. Even these cosmic rays have too high an energy to originate from the solar photosphere. The coronal cloud
in close proximity to the Sun
may be a source or create them as it bombards the chromosphere from above.
"In particular we recognize a first trace of Vela, brightest gamma and radio galactic source, and smeared sources along Galactic Plane and Center [as a source of ultra high energy cosmic rays (UHECR)]."
"The main correlated map is the 408 MHz one. The first astronomical source that seem to correlate is the main multiplet along CenA
. This AGN source, the nearest extragalactic one, sits in the same direction of a far Centaurus Cluster (part of the Super-Galactic Plane). The blurring by random galactic magnetic field might spread the nearest AGN event along the same Super-Galactic Plane, explaining the AUGER group miss-understanding ."
An atmospheric river forms over Hawai'i then heads toward California 10-11 April 2017. Credit: UW-CIMSS.
"Several times a year an atmospheric river [shown in the image on the right forming over Hawai'i]—a long, narrow conveyor belt of storms that stream in relentlessly from the Pacific Ocean—drops inches of rain or feet of snow on the U.S. west coast. Such a system triggered floods and mudslides in central and southern California this past weekend [2-3 February 2019]."
"Atmospheric rivers flow through the sky about a mile above the ocean surface, and may extend across a thousand miles of ocean to the coast. Some bring routine rain but the more intense systems can carry as much water as 15 Mississippi Rivers. The series of storms striking land can arrive for days or, occasionally, weeks on end. They hit west-facing coastlines worldwide, although the U.S. experiences more than most other national coasts."
The “atmospheric river scale” "ranks severity and impacts, from category 1 (weak) to category 5 (exceptional)."
"Without a scale, we really had no way to objectively communicate what would be a strong storm or a weak one."
"Scientists, the media and the public viewed atmospheric rivers as primarily a hazard, but the weaker ARs are quite beneficial. Water managers made it clear to us that a rating scale would be helpful."
"The scale, published Tuesday in the Bulletin of the American Meteorological Society
, ranks atmospheric rivers on five levels:"
- Category 1: Weak—primarily beneficial
- Category 2: Moderate—mostly beneficial, but also somewhat hazardous
- Category 3: Strong—balance of beneficial and hazardous
- Category 4: Extreme—mostly hazardous, but also beneficial (if persistent drought)
- Category 5—Exceptional—primarily hazardous
Alpha particle is detected in an isopropanol cloud chamber. Credit: Cloudylabs
Regarding alpha particles, as with beta and gamma particles/rays, the name used for the particle carries some mild connotations about its production process and energy, but these are not rigorously applied.
Asteroids in the solar system are categorized by size and number. Credit: Marco Colombo, DensityDesign Research Lab.
The center image is a log-log plot of frequency vs. size for asteroids in the solar system.
The image shows the hydrogen concentrations on the Moon detected by the Lunar Prospector. Credit: NASA.
Atomics are usually neutral atoms and molecules of a few atoms.
At right is the result of an all Moon survey by the Lunar Prospector using an onboard neutron spectrometer (NS). Cosmic rays impacting the lunar surface generate neutrons which in turn loose much of their energy in collisions with hydrogen atoms trapped within the Moon's surface.
Some of these thermal neutrons collide with the helium atoms within the NS to yield an energy signature which is detected and counted.
The NS aboard the Lunar Prospector has a surface resolution of 150 km.
This graph shows the power density spectrum of the extragalactic or cosmic gamma-ray background (CGB). Credit: email@example.com.
In the figure at right, CUVOB stands for the cosmic ultraviolet and optical background.
The diffuse extragalactic background light
(EBL) is all the accumulated radiation in the Universe due to star formation processes, plus a contribution from active galactic nuclei
(AGNs). This radiation
covers the wavelength range between ~ 0.1-1000 microns (these are the ultraviolet
, and infrared
regions of the electromagnetic spectrum). The EBL is part of the diffuse extragalactic background radiation (DEBRA), which by definition covers the overall electromagnetic spectrum. After the cosmic microwave background, the EBL produces the second-most energetic diffuse background, thus being essential for understanding the full energy balance of the universe.
This is Saturn imaged with the Stockholm Infrared Camera (SIRCA) in the H2O band. Credit: M. Gålfalk, G. Olofsson and H.-G. Florén, Nordic Optical Telescope.
At the right is Saturn imaged by the Stockholm Infrared Camera (SIRCA) in the H2O infrared band to show the presence of water vapor. The image is cut off near the top due to the presence of Saturn's rings.
The Sun's emission in the lowest UV bands, the UVA, UVB, and UVC bands, are of interest, as these are the UV bands commonly encountered from artificial sources on Earth. The shorter bands of UVC, as well as even more energetic radiation as produced by the Sun, generate the ozone in the ozone layer when single oxygen atoms produced by UV photolysis of dioxygen react with more dioxygen. The ozone layer is especially important in blocking UVB and part of UVC, since the shortest wavelengths of UVC (and those even shorter) are blocked by ordinary air.
"This graph shows the neutrons detected by a neutron detector at the University of Oulu in Finland from May 16 through May 18, 2012. The peak on May 17 represents an increase in the number of neutrons detected, a phenomenon dubbed a ground level enhancement or GLE. This was the first GLE since December of 2006. Credit: University of Oulu/NASA's Integrated Space Weather Analysis System"
A baryon is a composite subatomic particle bound together by the strong interaction, whereas leptons are not. The most familiar baryons are the protons and neutrons that make up most of the mass of the visible matter in the universe. Electrons (the other major component of the atom) are leptons. Each baryon has a corresponding antiparticle (antibaryon).
Baryonic matter is matter composed mostly of baryons (by mass), which includes atoms of any sort (and thus includes nearly all matter that may be encountered or experienced in everyday life).
The simulation attempts to answer how thunderstorms launch particle beams into space. Credit: NASA/Goddard Space Flight Center.
A number of subatomic reactions can be detected in astronomy that yield beta particles. The detection of beta particles or the reactions that include them in an astronomical situation is beta-particles astronomy.
Beta particles are high-energy, high-speed electrons or positrons.
Beta particles may be the key to fusion. "If the exterior of the capsule is maintained at a uniform temperature of about 19.5 K, the natural beta decay energy of the tritium will accomplish this through a process known as "beta layering." The very low energy beta particles from tritium decay deposit their energy very close to the location of the original tritium atoms."
"Beta-particles leaving the upper surface of the lunar sample could trigger the upper beta detector, while the lower beta-detector was triggered by beta particles from the lower surface of the sample."
Notation: let the symbol β− designate an unbound electron in motion.
Notation: let β+ designate an unbound positron in motion.
Notation: let TGF stand for a Terrestrial Gamma-ray Flash.
This picture from the Voyager 2 sequence shows two of the four cloud features which have been tracked by the Voyager cameras during the past two months. Credit: NASA.
Blue astronomy is focused on the wavelength range 450-475 nm.
Stars are often referred to by their predominant color. For example, blue stragglers
are found among the galactic halo globular clusters.
Blue main sequence stars that are metal poor ([Fe/H] ≤ -1.0) are most likely very different in origin from blue stragglers.
"[G]round-based UV [and blue astronomy] is a powerful facility for [the] study of [the] chemical evolution of [the] early Galaxy."
UV and B astronomy use radiation over the wavelength range 355.0-500.0 nm.
“To date, all of the reported hypervelocity stars (HVSs), which are believed to be ejected from the Galactic center, are blue and therefore almost certainly young.”
A trace amount of methane is also present. Prominent absorption bands of methane occur at wavelengths above 600 nm, in the red and infrared portion of the spectrum. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue,
although Neptune's vivid azure differs from Uranus's milder cyan. Since Neptune's atmospheric methane content is similar to that of Uranus, some unknown atmospheric constituent is thought to contribute to Neptune's colour.
This is a graph of the global mean atmospheric water vapor superimposed on an outline of the Earth. Credit: NASA.
The study of the abundance and reactions of chemical elements and molecules in the universe, as can be assessed b their interaction with radiation is part of astronomical radiation chemistry
, or radiation astrochemistry
This image shows a cumulus cloud above Lechtaler Alps, Austria. Credit: Glg
a "large white puffy cloud"
is called a cumulus
Cumulus clouds look white because the water droplets reflect and scatter the sunlight without absorbing other colors.
"On any given day, about half of Earth is covered by clouds, which reflect more sunlight than land and water. Clouds keep Earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth."
This gamma-ray spectrum contains the typical isotopes of the uranium-radium decay line. Credit: Wusel007
The peak at 40 keV is not from the mineral. From the color of the rock shown the yellowish mineral is likely to be autunite.
Autunite occurs as an oxidizing product of uranium minerals in granite pegmatites and hydrothermal deposits.
This image shows Comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/ UPM/DASP/IDA.
This image shows Comet 67P/Churyumov-Gerasimenko rotated around a vertical axis from the right. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/ UPM/DASP/IDA.
The image at the right is an optical astronomy image of the comet 67P/Churyumov-Gerasimenko. Rosetta's OSIRIS narrow-angle camera made the image on 3 August 2014 from a distance of 285 km. The image resolution is 5.3 metres/pixel.
The left image is rotated 90° from the right. The location of the right image is the front view of the left side just out of view in the left image. The object rotates by the right hand rule from the left image to the right.
Note that due to the evaporation of volatiles, the surface of the rocky object appears pitted or cratered.
The 15" refractor at Comanche Springs Astronomy Campus had its finder scope (a Stellarvue 80/9D achromat) equipped with a Baader Herschel Solar Wedge and a Solar Continuum Filter for today's transit of Venus. Credit: Jeff Barton from Richardson, TX, USA
Lyc photon or Ly continuum photon or Lyman continuum photon are a kind of photon emitted from stars. Hydrogen is ionized by absorption of Lyc photons. Lyc photons are in the ultraviolet portion of the electromagnetic spectrum of the hydrogen atom and immediately next to the limit of the Lyman series of the spectrum with wavelengths that are shorter than 91.1267 nanometres and with energy above 13.6 eV.
Cosmic Ray Intensity (blue) and Sunspot Number (green) is shown from 1951 to 2006 Credit: University of New Hampshire.
The graph on the right shows an inverse correlation between sunspot numbers (solar activity) and neutron production from galactic cosmic rays.
There is "a correlation between the arrival directions of cosmic rays with energy above 6 x 1019
electron volts and the positions of active galactic nuclei (AGN) lying within ~75 megaparsecs."
The Oh-My-God particle
was observed on the evening of 15 October 1991 over Dugway Proving Ground, Utah. Its observation was a shock to astrophysicists, who estimated its energy to be approximately 3×
(50 joules)—in other words, a subatomic particle with kinetic energy equal to that of a baseball (142 g or 5 oz) traveling at 100 km/h (60 mph).
It was most probably a proton with a speed very close to the speed of light
, so close, in fact, [(1 − 5×
) × c
], that in a year-long race between light and the cosmic ray, the ray would fall behind only 46 nanometers (5×
light-years), or 0.15 femtoseconds (1.5×
Malaspina Glacier in southeastern Alaska is considered the classic example of a piedmont glacier. Credit: NASA.
A cryometeor is a meteor of variable size that has been radiated and is still moving composed of ice, e.g. water or methane ice.
A cryometeor that has stopped moving has become a cryometeorite.
Def. a glacier that occurs on a gentle slope leading from the base of mountains to a region of flat land, any region of foothills of a mountain range, or formed or lying at the foot of a mountain range is called a piedmont glacier.
Recent changes in Comet Lulin's greenish coma and tails are shown in these two panels taken on January 31st (top) and February 4th (bottom) 2009. In both views the comet has an apparent antitail to the left of the coma of dust. Credit: Joseph Brimacombe, Cairns, Australia.
Perhaps the most prominent cyan planetary source is Uranus, which has only been visited by the space probe Voyager 2. More recent images come from the Hubble Space Telescope in orbit around Earth.
Methane possesses prominent absorption bands in the visible and near-infrared (IR) making Uranus aquamarine
or cyan in color.
“During the Halley Monitoring Program at La Silla from Feb.17 to Apr.17,1986 ... In the light of the neutral CN-radical a continuous formation and expansion of [cyan] gas-shells could be observed.”
“The gas-expansion velocity decreases with increasing heliocentric distance from 1 km/s in early March to 0.8 km/s in April.”
Shown at right, "Lulin's green color comes from the gases that make up its Jupiter-sized atmosphere. Jets spewing from the comet's nucleus contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2
). Both substances glow green when illuminated by sunlight"
The electric blue glow of electricity results from the spectral emission of the excited ionized atoms (or excited molecules) of air (mostly oxygen and nitrogen) falling back to unexcited states, which happens to produce an abundance of electric blue light. This is the reason electrical sparks in air, including lightning, appear electric blue. It is a coincidence that the color of Cherenkov radiation and light emitted by ionized air are a very similar blue despite their very different methods of production.
This tree diagram shows the relationship between types and classification of most common particle detectors. Credit: Wdcf
Radiation detectors provide a signal that is converted to an electric current. The device is designed so that the current provided is proportional to the characteristics of the incident radiation.
There are detectors that provide a change in substance as the signal and these may be automated to provide an electric current or quantified proportional to the amount of new substance.
Diagram shows the electronic and nuclear stopping power for aluminum ions in aluminum. Credit: HPaul.
This is an illustration of the slowing down of a single ion in a solid material. Credit: Kai Nordlund.
A Bragg curve of 5.49 MeV alpha particles in air is illustrated. Credit: Helmut Paul.
a "frequency of occurrence or extent of existence"
or "the relative arrangements of the elements of a statistical population based on some criterion, as frequency, time, or location"
is called a distribution
"the fraction of photoelectric events which end up in the photopeak of the measured energy spectrum"
is called the photopeak efficiency
Ending up in the photopeak means within ± 1 full-width at half maximum (FWHM) of the peak of the distribution.
"The peak to valley ratio is commonly used as a token for ε."
"Another common practice is to fit an exponential function to the “valley” and to extrapolate the fit to lower pulse heights to estimate the fraction of counts hidden in the Compton continuum."
"We have used a calibrated Cs137
source to determine the absolute photopeak efficiency at 662 keV. The source was placed at a sufficiently large distance from the detector so that the event rate was low and the dead time was less than 20%. Based on a log-histogram of the time intervals between events, the dead-time has been estimated to a fractional accuracy of better than 5%. We determine the photopeak efficiency by comparing the dead-time corrected event rate in the photopeak with the theoretical expectation assuming a perfect detector."
Def. the average energy loss of the particle per unit path length is called the stopping power.
Def. the slowing down of a projectile ion due to the inelastic collisions between bound electrons in the medium and the ion moving through it is called the electronic stopping power.
Def. the elastic collisions between the projectile ion and atoms in the sample involving the interaction of the ion with the nuclei in the target is called the nuclear stopping power.
The second figure on the right shows the electronic and nuclear stopping power of aluminum single crystal for aluminum ions. These stopping powers are versus particle energy per nucleon. The maximum of the nuclear stopping curve typically occurs at energies of the order of 1 keV per nucleon.
The second figure at right illustrates the slowing down of a single ion in a solid material.
In the beginning of the slowing-down process at high energies, the ion is slowed down mainly by electronic stopping, and it moves almost in a straight path. When the ion has slowed down sufficiently, the collisions with nuclei (the nuclear stopping) become more and more probable, finally dominating the slowing down. When atoms of the solid receive significant recoil energies when struck by the ion, they will be removed from their lattice
positions, and produce a cascade of further collisions
in the material. These collision cascades
are the main cause of damage production during ion implantation in metals and semiconductors.
When the energies of all atoms in the system have fallen below the threshold displacement energy
, the production of new damage ceases, and the concept of nuclear stopping is no longer meaningful. The total amount of energy deposited by the nuclear collisions to atoms in the materials is called the nuclear deposited energy.
The inset in the figure shows a typical range distribution of ions deposited in the solid. The case shown here might for instance be the slowing down of a 1 MeV silicon ion in silicon. The mean range for a 1 MeV ion is typically in the micrometer range.
Third right is an illustration of a Bragg curve. The stopping power and hence, the density of ionization, usually increases toward the end of range and reaches a maximum, the Bragg peak, shortly before the energy drops to zero.
The electric vectors of PKS0521-36 show clear structure and alignment. Credit: Keel.
"The emission of electromagnetic radiation from a superluminal (faster-than-light in vacuo) charged particle [is such] that no physical principle forbids emission by extended, massless superluminal sources. A polarization current density (dP
/dt; see Maxwell's fourth equation) can provide such a source; the individual charged particles creating the polarization do not move faster than c, the speed of light, and yet it is relatively trivial to make the envelope of the polarization current density to do so."
The "emitted radiation has many unusual characteristics, including: (i) the intensity of some components decays as the inverse of the distance from the source, rather than as 1/(distance)2 (i.e. these components are non-spherically-decaying); (ii) the emission is tightly beamed, the exact direction of the beam depending on the source speed; and (iii) the emission contains very high frequencies not present in the synthesis of the source. Note that the non-spherically decaying components of the radiation do not violate energy conservation. They result from the reception, during a short time period, of radiation emitted over a considerably longer period of (retarded) source time; their strong electromagnetic fields are compensated by weak fields elsewhere ."
The "emission occupies a very small polar angular width of order 0.8 degrees in the far field. Based on these findings, we suggest that a superluminal source could act as a highly directional transmitter of MHz or THz signals over very long distances."
"The magnetic field is well-ordered in many jets, as shown by polarization measurements. Synchrotron radiation can be very highly polarized (50%) if the field is globally ordered, and some sources [approach] this level. The electric vectors show clear structure and alignment; an especially common pattern is for the field lines to be along the jet in the inner portions and transition to an azimuthal configuration farther out. This is seen in [PKS0521-36 at 2 cm]."
This is a colour composite image of RCW120. Credit: ESO/APEX/DSS2/ SuperCosmos/ Deharveng(LAM)/ Zavagno(LAM).
Radiation astronomy is often performed using electromagnetics. Electromagnetics are most familiar as light, or electromagnetic radiation.
The image at right is a colour "composite image of RCW120. It reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps where new stars are then formed. The 870-micron submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope. Here, the submillimetre emission is shown as the blue clouds surrounding the reddish glow of the ionised gas (shown with data from the SuperCosmos H-alpha survey). The image also contains data from the Second Generation Digitized Sky Survey (I-band shown in blue, R-band shown in red)." Electromagnetic radiation astronomy
is a broader concept, physics subject heading used by the American Physical Society (APS).
Aurorae are mostly caused by energetic electrons precipitating into the atmosphere.
Credit: Samuel Blanc
Although electron astronomy
is usually not recognized as a formal branch of astronomy, the measurement of electron fluxes help to understand a variety of natural phenomena.
Particles such as electrons are used as tracers of cosmic magnetic fields.
"From a plasma-physics point of view, the particles represent the correct way to identify magnetic field lines."
"The suprathermal electrons in the solar wind and in solar particle events have excellent properties for this application: they move rapidly, they remain tightly bound to their field lines, and they may arrive "scatter-free" even at low energies, and from deep in the solar atmosphere (Lin 1985)."
These electrons "provide remote-sensing observations of distant targets in the heliosphere - the Sun, the Moon, Jupiter, and various heliospheric structures."
""[E]lectron astronomy" has an interesting future".
A delta ray is characterized by very fast electrons produced in quantity by alpha particles or other fast energetic charged particles knocking orbiting electrons out of atoms. Collectively, these electrons are defined as delta radiation when they have sufficient energy to ionize further atoms through subsequent interactions on their own.
"The conventional procedure of delta-ray counting to measure charge (Powell, Fowler, and Perkins 1959), which was limited to resolution σz
= 1-2 because of uncertainties of the criterion of delta-ray ranges, has been significantly improved by the application of delta-ray range distribution measurements for 16
O and 32
S data of 200 GeV per nucleon (Takahashi 1988; Parnell et al.
Here, the delta-ray tracks in emulsion chambers have been used for "[d]irect measurements of cosmic-ray nuclei above 1 TeV/nucleon ... in a series of balloon-borne experiments".
The Hubble Space Telescope [Advanced Camera for Surveys] ACS image has H-alpha emission of the Red Rectangle shown in blue. Credit: ESA/Hubble and NASA.
"[T]he extended red emission (ERE) [is] observed in many dusty astronomical environments, in particular, the diffuse interstellar medium of the Galaxy. ... silicon nanoparticles provide the best match to the spectrum and the efficiency requirement of the ERE."
The best empirical evidence that supermassive black holes do really exist is the orbits of these stars around the center of the Milky Way
. Credit: Stefan Gillessen, Reinhard Genzel, Frank Eisenhauer, ESO.
A list or catalog of the specific principles incorporated into the development of the various radiation astronomies may be helpful to students and researchers alike.
These principles can be included in mathematical astronomy
, astrophysics, astrochemistry
, and theoretical radiation astronomy as summaries, or, a lecture on empirical radiation astronomy
This is an image of Johannes Vermeer's The astronomer. Credit: www.essentialvermeer.com : Home
Radiation astronomy entities, radiation entities, are any astronomical persons or things that have separate and distinct existences in empirical, objective or conceptual reality.
Some of them, like the astronomers of today, or at any time in the past, are relatively known. But there are many entities that are far less known or understood, such as the observers of ancient times who suggested that deities occupied the sky or the heavens. Likewise, these alleged deities may be entities, or perhaps something a whole lot less.
Astronomical X-ray entities are often discriminated further into sources or objects when more information becomes available, including that from other radiation astronomies.
A researcher who turns on an X-ray generator to study the X-ray emissions in a laboratory so as to understand an apparent astronomical X-ray source is an astronomical X-ray entity. So is one who writes an article about such efforts or a computer simulation to possibly represent such a source.
"The X-ray luminosity of the dominant group
[an entity] is an order of magnitude fainter than that of the X-ray jet."
This is a fireball meteor trail with some burning still visible above the Urals city of Chelyabinsk, Russia, on February 15, 2013. Credit: Reuters/www.chelyabinsk.ru.
On the right is a visual astronomy
image of a fireball trail with some burning still visible from a meteor as it passed overhead in Chelyabinsk, Russia, on February 15, 2013.
This image shows "[t]he trail of a falling object ... seen above the Urals city of Chelyabinsk [on] February 15, 2013".
This Galaxy Evolution Explorer (GALEX) image of the spiral galaxy Messier 81 is in ultraviolet light. Credit: NASA/JPL-Caltech/J. Huchra (Harvard-Smithsonian CfA).
The radiation astronomy of galaxies generally is about the galaxy as a radiated or radiation emitting astronomical object. The stellar aspects of individual galaxies are in galaxies of stars
A galaxy is often perceived as a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.
Galaxies range in size from dwarfs with just a few hundred million (108
) stars to giants with one hundred trillion (1014
each orbiting its galaxy's center of mass.
Galaxies are categorized according to their visual morphology as elliptical,
spiral, or irregular.
The number of galaxies in the observable universe has increased from a previous estimate of 200 billion (2e11)
to a suggested 2 trillion (2e12) or more,
containing more stars
than all the grains of sand on planet Earth.
The universe within 1 billion light-years (307 Mpc) of Earth is shown to contain the local superclusters, galaxy filaments and voids. Credit: Richard Powell.
"Galaxies and clusters of galaxies are not uniformly distributed in the Universe, instead they collect into vast clusters and sheets and walls of galaxies interspersed with large voids in which very few galaxies seem to exist. The map above shows many of these superclusters including the Virgo supercluster - the minor supercluster of which our galaxy is just a minor member. The entire map is approximately 7 percent of the diameter of the entire visible Universe."
The Moon is seen by the Compton Gamma Ray Observatory
, in gamma rays of greater than 20 MeV. Credit: D. J. Thompson, D. L. Bertsch (NASA/GSFC), D. J. Morris (UNH), R. Mukherjee (NASA/GSFC/USRA).
Most astronomical gamma-rays are thought to be produced not from radioactive decay, however, but from the same type of accelerations of electrons, and electron-photon interactions, that produce X-rays in astronomy (but occurring at a higher energy in the production of gamma-rays).
For gamma-ray astronomy
, the Vela satellites were the first devices ever to detect cosmic gamma ray bursts.
) are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies
. They are the most luminous electromagnetic events known to occur in the universe
. Bursts can last from ten milliseconds to several minutes, although a typical burst lasts 20–40 seconds. The initial burst is usually followed by a longer-lived "afterglow" emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio).
This Chandra X-ray Observatory image is the first look at X-rays from Mars. Credit: NASA/CXC/MPE/K.Dennerl et al.
"In the sparse upper atmosphere of Mars, about 120 (75 miles) kilometers above its surface, the observed X-rays [shown in the image at right] are produced by fluorescent radiation from oxygen atoms."
"X-radiation from the Sun impacts oxygen atoms, knock electrons out of the inner parts of their electron clouds, and excite the atoms to a higher energy level in the process. The atoms almost immediately return to their lower energy state and may emit a fluorescent X-ray in this process with an energy characteristic of the atom involved - oxygen in this case. A similar process involving ultraviolet light produces the visible light from fluorescent lamps."
"The X-ray power detected from the Martian atmosphere is very small, amounting to only 4 megawatts, comparable to the X-ray power of about ten thousand medical X-ray machines. Chandra was scheduled to observe Mars when it was only 70 million kilometers from Earth, and also near the point in its orbit when it is closest to the Sun."
"At the time of the Chandra observation, a huge dust storm developed on Mars that covered about one hemisphere, later to cover the entire planet. This hemisphere rotated out of view over the course of the 9-hour observation but no change was observed in the X-ray intensity, implying that the dust storm did not affect the upper atmosphere."
"The astronomers also found evidence for a faint halo of X-rays that extends out to 7,000 kilometers above the surface of Mars. Scientists believe the X-rays are produced by collisions of ions racing away from the Sun (the solar wind) with oxygen and hydrogen atoms in the tenuous exosphere of Mars."
The Caltech Submillimeter Observatory at Mauna Kea Observatory has a 10.4 m (34 ft) dish. Credit: Samuel Bouchard
from Quebec City, Canada.
Each individual or small group of astronomical knowledge recorders among the hominins after some effort has realized that they are on the surface of a planet, an approximately spheroidal object. Further, when any of them study the sky, they have realized they are only sensing a small portion relative to their location (such as in the enjoyment of backyard astronomy
). To combine what they've learned, when they get together to discuss it or record it, they have to locate that knowledge where that knowledge occurred. This locating eventually included the radiation received to form the knowledge and science of astronomical radiation geography
Geographical radiation astronomy is the study of the effect of geography on radiation astronomy. Both astronomical radiation geography and geographical radiation astronomy are part of astrogeography, or astrography.
The images show LIGO and Livingston, Louisiana, measurement of gravitational waves. Credit: B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration).
This photo shows the Livingston LIGO detector. Credit: Caltech/MIT/LIGO Laboratory.
This gravitational wave spectrum includes sources and detectors. Credit: NASA Goddard Space Flight Center.
appears to be cylindrical waves of radiation produced by relativistic, undulatory gravitational fields in Euclidean space.
As the gravitational interaction is 10-36 that of the electromagnetic interaction to produce gravitational radiation requires a massive oscillator.
At right are the results from the first gravitational radiation detection. The images show the radiation signals received by the Laser Interferometer Gravitational Observatory (LIGO) instruments at Hanford, Washington (left) and Livingston, Louisiana (right) and comparisons of these signals to the signals expected due to a black hole merger event.
The wavelength of the gravitational waves is given by for example: 3 x 108 m‧s-1/400 Hz = 750,000 m, which is way longer than radio waves but expected for such a weak oscillator. 35 Hz corresponds to 8,600,000 m.
LIGO operates two detectors located 3000 km (1800 miles) apart: One in eastern Washington near Hanford, and the other near Livingston, Louisiana. The photo on the left shows the Livingston detector.
"According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide at nearly half the speed of light and form a single, more massive black hole, converting a portion of the combined black holes' mass to energy, according to Einstein's formula E=mc2
. This energy is emitted as a final strong burst of gravitational waves. These are the gravitational waves that LIGO observed."
"LIGO’s twin interferometers bounce laser beams between mirrors at the opposite ends of 4-kilometre-long vacuum pipes that are set perpendicularly to each other. A gravitational wave passing through will alter the length of one of the arms, causing the laser beams to shift slightly out of sync."
Later detection confirmed the fusion of two massive stellar-sized objects, a binary neutron star merger.
"According to Einstein's field equations, photon matter subject to quadruple oscillations is a source of gravitational waves."
"In this work, we present a solution to the first stage of a new two-stage global treatment of the vacuum binary black hole problem [1, 2]. The approach, based upon characteristic evolution, has been carried out in the regime of Schwarzschild perturbations where advanced and retarded solutions of the linearized problem can be rigorously identified . Computational experiments are necessary to study the applicability of the approach to the nonlinear regime. From a time-reversed viewpoint, this first stage is equivalent to the determination of the outgoing radiation emitted from the fission of a white hole in the absence of ingoing radiation. This provides the physically correct “retarded” waveform for a white hole fission, were such events to occur in the universe. Although there is no standard astrophysical mechanism for producing white holes from a nonsingular matter distribution, white holes of primordial or quantum gravitational origin cannot be ruled out."
"This fission problem has a simpler formulation as a characteristic initial value problem than the black hole merger problem. The boundary of the (conformally compactified) exterior spacetime contains two null hypersurfaces where boundary conditions must be satisfied: past null infinity I−, where the incoming radiation must vanish, and the white hole event horizon H−, which must describe a white hole, which is initially in equilibrium with no ingoing radiation and then distorts and ultimately fissions into two white holes with the emission of outgoing gravitational waves."
An almost identical signal could originate from a comparable much more massive neutron star fission.
"This is an exciting time to study gravitation, astrophysics and cosmology. Through challenging cosmic microwave background (CMB) and supernovae observations cosmology has been turned on its head. Gravitational radiation astronomy should be the next contributor to this revolution in astrophysics and cosmology."
A picture of the solar corona taken with the LASCO C1 coronagraph. The image is color coded for the doppler shift of the FeXIV 530.8 nm line. Credit: NASA and NRL.
Green objects or emission lines in the green portion of the visible spectrum are the subject of green astronomy
In the image at right the iron (Fe XIV) green line is followed by doppler imaging to show associated relative coronal plasma velocity towards (-7 km/s side) and away from (+7 km/s side) the large angle spectrometric coronagraph LASCO satellite camera.
"Carroll and McCormack (1972) in Dublin reported complex spectra in the blue and green wavelength regions of both FeH and FeD".
For elongated dust particles in cometary comas an investigation is performed at 535.0 nm (green) and 627.4 nm (red) peak transmission wavelengths of the Rosetta spacecraft's OSIRIS Wide Angle Camera broadband green and red filters, respectively.
"In the green, the polarization of the pure silicate composition qualitatively appears a better fit to the shape of the observed polarization curves".
"[B]ut they are characterized by a high albedo."
The silicates used to model the cometary coma dust are olivene (Mg-rich is green) and the pyroxene, enstatite.
In December 2006, seven papers were published in the scientific journal, Science
, discussing initial details of the sample analysis. Among the findings are: a wide range of organic compounds, including two that contain biologically usable nitrogen; indigenous aliphatic hydrocarbons with longer chain lengths than those observed in the diffuse interstellar medium; abundant amorphous silicates in addition to crystalline silicates such as olivine and pyroxene, proving consistency with the mixing of solar system and interstellar matter, previously deduced spectroscopically from ground observations;
hydrous silicates and carbonate minerals were found to be absent, suggesting a lack of aqueous processing of the cometary dust; limited pure carbon (CHON) was also found in the samples returned; methylamine and ethylamine was found in the aerogel but was not associated with specific particles.
The eight toroid magnets can be seen surrounding the calorimeter that is later moved into the middle of the detector. Credit: Maximilien Brice.
are subatomic particles of a type including baryons
that can take part in the strong interaction
and may be useful in radiation astronomy.
At right a person works lower center left in front of the huge ATLAS detector, one of six detectors attached to the Large Hadron Collider at CERN.
The irregular galaxy NGC 1427A is passing through the Fornax cluster at nearly 600 kilometers per second (400 miles per second). Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA).
"The irregular galaxy NGC 1427A is a spectacular example of the resulting stellar rumble. Under the gravitational grasp of a large gang of galaxies, called the Fornax cluster, the small bluish galaxy is plunging headlong into the group at 600 kilometers per second or nearly 400 miles per second."
"Galaxy clusters, like the Fornax cluster, contain hundreds or even thousands of individual galaxies. Within the Fornax cluster, there is a considerable amount of gas lying between the galaxies. When the gas within NGC 1427A collides with the Fornax gas, it is compressed to the point that it starts to collapse under its own gravity. This leads to formation of the myriad of new stars seen across NGC 1427A, which give the galaxy an overall arrowhead shape that appears to point in the direction of the galaxy's high-velocity motion."
Stonehenge is a Neolithic monument that may have functioned as a celestial observatory.
, or hominins have apparently been on Earth for around seven to eight million years, at least somewhere in Africa
and elsewhere. Fortunately and deliberately, many of these have worked out ways to record knowledge about the objects or entities in the sky observed by the radiation they produce. Original research/Radiation astronomy
as an observational science
has a long radiation history
This image shows a late-summer rainstorm in the village Lunde, The north of Funen, Denmark. Credit: Malene Thyssen
The nearly black color of the cloud's base indicates the foreground cloud is probably cumulonimbus.
The Hubble Space Telescope image shows four high-velocity, runaway stars plowing through their local interstellar medium. Credit: NASA - Hubble's Advanced Camera for Surveys.
Def. a star moving faster than 65 km/s to 100 km/s relative to the average motion of the stars in the Sun's neighbourhood is called a high-velocity star.
Def. a high-velocity star moving through space with an abnormally high velocity relative to the surrounding interstellar medium is called a runaway star.
Def. a star whose elliptical orbit takes it well outside the plane of [its galaxy] at steep angles is called a halo star.
This is a three-color far-infrared image of M51, the Whirlpool Galaxy. Credit: ESA and the PACS Consortium.
The wavelength of infrared light ranges from 0.75 to 300 micrometers. Infrared falls in between visible radiation, which ranges from 380 to 750 nanometers, and terahertz radiation submillimeter waves.
Infrared and optical astronomy
are often practiced using the same telescopes, as the same mirrors or lenses are usually effective over a wavelength range that includes both visible and infrared light.
Far-infrared astronomy deals with objects visible in far-infrared radiation extending from 30 micron (µm) towards submillimeter wavelengths around 450 µm.
Huge, cold clouds of gas and dust in [the Milky Way] our own galaxy, as well as in nearby galaxies
, glow in far-infrared light. This is due to thermal radiation of interstellar dust contained in molecular clouds.
Visually dark infrared sources can be radiative cosmic dust, hydrogen gas such as an H II region (e.g. the Orion Nebula), an H I region of hydrogen, a molecular cloud, or a coronal cloud.
There are about 1,892,100 infrared (IR) objects in the SIMBAD database. Some of these like IRAS 20542+3631 are only IR objects. 1RXS J205444.6+361116 is an IR and an X-ray object only. These objects are visibly dark infrared sources. As is 2MASS J21074764+3802561, which is an IR and UV object only.
Positrons from a terrestrial gamma ray flash are detected by the Fermi gamma ray telescope. Credit: NASA Goddard Space Flight Center.
Intensity astronomy focuses on creating a sufficient intensity for a desired property or characteristic that a signal may be converted in a detector to an electric current.
The Kuiper belt
is a region of the solar system extending from the orbit of Neptune (at 30 AU to approximately 60 AU from the Sun.
It consists mainly of small bodies
"[B]roadband optical photometry of Centaurs and Kuiper Belt objects from the Keck 10 m, the University of Hawaii 2.2 m, and the Cerro Tololo InterAmerican (CTIO) 1.5 m telescopes [shows] a wide dispersion in the optical colors of the objects, indicating nonuniform surface properties. The color dispersion [may] be understood in the context of the expected steady reddening due to bombardment by the ubiquitous flux of cosmic rays."
In the image at right, objects in the main part of the Kuiper belt are coloured green, while scattered objects are coloured orange. The four outer planets are blue. Neptune's few known trojans
are yellow, while Jupiter's are pink. The scattered objects between Jupiter's orbit and the Kuiper belt are known as centaurs
. The scale is in astronomical units
. The pronounced gap at the bottom is due to difficulties in detection against the background of the plane of the Milky Way
Positions are accurate for January 1st, 2000 (J2000 epoch
) with some caveats:
For planets, positions should be exact.
For minor bodies, positions are extrapolated from other epochs assuming purely Keplerian motion
. As all data is from an epoch between 1993 and 2007, this should be a reasonable approximation.
Radial "spokes" of higher density in this image, or gaps in particular directions are due to observational bias (i.e. where objects were searched for), rather than any real physical structure. The pronounced gap at the bottom is due to obscuration by the band of the Milky Way.
This image shows a cluster of yellow galaxies near the middle of the photograph. Credit: STScl/NASA.
The image at right shows several blue, loop-shaped objects that are multiple images of the same galaxy, duplicated by the gravitational lens
effect of the cluster of yellow galaxies near the middle of the photograph. The lens is produced by the cluster's gravitational field that bends light to magnify and distort the image of a more distant object.
Representation of upper-atmospheric lightning and electrical-discharge phenomena are displayed. Credit: Abestrobi
An illustration of different kinds of transient luminous events (TLEs) is displayed. Credit: Carlos Miralles (AeroVironment) and Tom Nelson (FMA).
Lightning is more than ground-to-cloud electron transfer.
"Cloud flashes sometimes have visible channels that extend out into the air around the storm (cloud-to-air or CA), but do not strike the ground. The terms sheet lightning or intra-cloud lightning (IC) refers to lightning embedded within a cloud that lights up as a sheet of luminosity during the flash. A related term, heat lightning, is lightning or lightning-induced illumination that is too far away for thunder to be heard. Lightning can also travel from cloud-to-cloud (CC). Spider lightning refers to long, horizontally traveling flashes often seen on the underside of stratiform clouds."
"Large thunderstorms are capable of producing other kinds of electrical phenomena called transient luminous events (TLEs) that occur high in the atmosphere. They are rarely observed visually and not well understood. The most common TLEs include red sprites, blue jets, and elves."
The illustration on the left labels Elves, Sprites, and tendrils, a stratiform region producing positive cloud-to-ground flashes with spider lightning on the right to conventional cloud-to-air discharge, upward superbolt, blue jets and negative cloud-to-ground flash near convective core. Approximate altitudes in the Earth's atmosphere and ionosphere are indicated.
This is a detailed, photo-like view of Earth based largely on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. Credit: Robert Simmon and Marit Jentoft-Nilsen, NASA.
precipitation products of the condensation
of atmospheric water vapour are called hydrometeors
"Condensation or sublimation of atmospheric water vapor produces a hydrometeor. It forms in the free atmosphere, or at the earth's surface, and includes frozen water lifted by the wind. Hydrometeors which can cause a surface visibility reduction, generally fall into one of the following two categories:
- Precipitation. Precipitation includes all forms of water particles, both liquid and solid, which fall from the atmosphere and reach the ground; these include: liquid precipitation (drizzle and rain), freezing precipitation (freezing drizzle and freezing rain), and solid (frozen) precipitation (ice pellets, hail, snow, snow pellets, snow grains, and ice crystals).
- Suspended (Liquid or Solid) Water Particles. Liquid or solid water particles that form and remain suspended in the air (damp haze, cloud, fog, ice fog, and mist), as well as liquid or solid water particles that are lifted by the wind from the earth’s surface (drifting snow, blowing snow, blowing spray) cause restrictions to visibility. One of the more unusual causes of reduced visibility due to suspended water/ice particles is whiteout, while the most common cause is fog."
The image shows the Orion nebula surrounded by a ring of dust. Credit: NASA/JPL-Caltech/T. Megeath(University of Toledo).
Def. a suspension of dry dust in an atmosphere is called a lithometeor.
"A lithometeor consists of solid particles suspended in the air or lifted by the wind from the ground."
"A lithometeor is the general term for particles suspended in a dry atmosphere; these include dry haze, smoke, dust, and sand."
"Dry haze is an accumulation of very fine dust or salt particles in the atmosphere; it does not block light, but instead causes light rays to scatter. Dry haze particles produce a bluish color when viewed against a dark background, but look yellowish when viewed against a lighter background. This light-scattering phenomenon (called Mie scattering
) also causes the visual ranges within a uniformly dense layer of haze to vary depending on whether the observer is looking into the sun or away from it."
Heavy metal pollution may occur in lithometeors.
"The rise of airborne dust is constantly augmenting from the desert (Bilma) to the southern Sahelian stations (Niamey) where it has increased by a factor five. ... the Sahelian zone with airborne dust during the 80s ... All stations have recorded a general increase of wind velocity. The increase of lithometeors frequency as well as the wind velocity during the drought period is not explained by the aridification."
This animation depicts the collision between our Milky Way galaxy and the Andromeda galaxy. Credit: Visualization Credit: NASA; ESA; and F. Summers, STScI; Simulation Credit: NASA; ESA; G. Besla, Columbia University; and R. van der Marel, STScI.
Most of the mathematics needed to understand the information acquired through astronomical radiation observation comes from physics. But, there are special needs for situations that intertwine mathematics with phenomena that may not yet have sufficient physics to explain the observations. Both uses constitute radiation mathematics, or astronomical radiation mathematics, or a portion of mathematical radiation astronomy.
Astronomical radiation mathematics is the laboratory mathematics such as simulations that are generated to try to understand the observations of radiation astronomy.
The mathematics needed to understand radiation astronomy starts with arithmetic and often needs various topics in calculus and differential equations to produce likely models.
Comparison of the LHCb data on B0 meson production, both for central and for forward rapidities, with the theoretical predictions from POWHEG and aMC@NLO. Credit: Rhorry Gauld, Juan Rojo, Luca Rottoli and Jim Talbert.
A meson is a composite subatomic particle "bound together by the strong interaction.
Because mesons are composed of sub-particles, they have a physical size, with a radius roughly one femtometre, which is about 2/3 the size of a proton or neutron. All mesons are unstable, with the longest-lived lasting for only a few hundredths of a microsecond. Charged mesons decay (sometimes through intermediate particles) to form electrons and neutrinos. Uncharged mesons may decay to photons.
Mesons are not produced by radioactive decay, but appear in nature only as short-lived products of very high-energy interactions in matter. In cosmic ray interactions, for example, such particles are ordinary protons and neutrons. Mesons are also frequently produced artificially in high-energy particle accelerators that collide protons, anti-protons, or other particles.
In nature, the importance of lighter mesons is that they are the associated quantum-field particles that transmit the nuclear force, in the same way that photons are the particles that transmit the electromagnetic force.
Each type of meson has a corresponding antiparticle (antimeson) in which quarks are replaced by their corresponding antiquarks and vice-versa.
Mesons are subject to both the weak and strong interactions. Mesons with net electric charge also participate in the electromagnetic interaction.
While no meson is stable, those of lower mass are nonetheless more stable than the most massive mesons, and are easier to observe and study in particle accelerators or in cosmic ray experiments. They are also typically less massive than baryons, meaning that they are more easily produced in experiments, and thus exhibit certain higher energy phenomena more readily than baryons composed of the same quarks would.
This image is a cross-section of the Laguna Manantiales meteorite showing Widmanstätten patterns. Credit: Aram Dulyan
Widmanstätten patterns, also called Thomson structures, are unique figures of long nickel-iron crystals, found in the octahedrite iron meteorites and some pallasite]]s. They consist of a fine interleaving of kamacite and taenite bands or ribbons called lamellæ. Commonly, in gaps between the lamellæ, a fine-grained mixture of kamacite and taenite called plessite can be found.
This is a scanned photograph of the bolide EN131090, originally captured on a glass photographic plate. Credit: European Fireball Network.
This is a scanned photograph on the right of the bolide EN131090, originally captured on a glass photographic plate. The Earth-grazing meteoroid flew above Czechoslovakia and Poland on 13 October 1990 and left to space again. It was taken by an all-sky camera equipped with a fish-eye objective Zeiss Distagon 3.5/30mm located at the hydrometeorological station at Červená hora, Czechoslovakia (now in the Czech Republic). The bolide travels from the south to the north and its track is interrupted by a shutter rotating 12.5 times per second, which allows determining its speed.
"As of 2011 the International Astronomical Union officially defines a meteoroid as a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom".
This meteor image of October 17, 2012, is prior to the meteorite fall on the same day. Credit: Paola-Castillo; and Petrus M. Jenniskens, SETI Institute/NASA ARC.
A meteor is the visible path of a meteoroid that has entered the Earth's atmosphere.
Although there are many definitions of a meteor ranging from any atmospheric phenomenon to a fast-moving streak of light in the night sky caused by the entry of extraterrestrial matter into the earth's atmosphere: A shooting star or falling star, for radiation astronomy, an alternative definition is used.
Def. any natural object radiating through a portion or all of the Earth's or another natural object's atmosphere is called a meteor.
A hypervelocity star "snow-plowing" through the interstellar medium
of a galaxy is a meteor and the subject of meteor astronomy.
Meteor astronomy (radiated meteors) is radiation astronomy of large matter objects moving rapidly relative to apparently fixed objects.
A meteor may be as small as an electron. Astronomical objects that are atoms, nuclei, or subatomic particles are part of cosmic-ray astronomy.
The Aurigid meteor shower is observed by a group of astronomers on a NASA mission at 47,000 feet. Credit: Jeremie Vaubaillon, Caltech, NASA.
Meteors may occur in showers, which arise when the Earth passes through a trail of debris left by a comet, or as "random" or "sporadic" meteors, not associated with a specific single cause. A number of specific meteors have been observed, largely by members of the public and largely by accident, but with enough detail that orbits of the meteoroids producing the meteors have been calculated. All of the orbits passed through the asteroid belt.
"Named meteor showers recur at approximately the same dates each year. They appear to "radiate" from a certain point in the sky (the radiant) and vary in the speed, frequency and brightness of the meteors."
As of November 2018, there are 112 established meteor showers.
A view of the Milky Way galaxy in microwaves is captured by the European Space Agency's Planck satellite. Credit: ESA/NASA/JPL-Caltech.
Radiation astronomy specifically focused at the microwave portion of the electromagnetic spectrum is microwave astronomy.
, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.
This broad definition includes both UHF and Extremely high frequency (EHF) (millimeter waves), and various sources use different boundaries.
In all cases, microwave includes the entire super high frequency (SHF) band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3 mm).
This is an image of the mineral pitchblende, or uraninite. Credit: Geomartin
These crystals are uraninite from Trebilcock Pit, Topsham, Maine. Credit: Robert Lavinsky
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely [uranium dioxide] UO2, but also contains [uranium trioxide] UO3 and oxides of lead, thorium, and rare earth elements. It is most commonly known as pitchblende (from pitch, because of its black color. All uraninite minerals contain a small amount of radium as a radioactive decay product of uranium. Uraninite also always contains small amounts of the lead isotopes 206Pb and 207Pb, the end products of the decay series of the uranium isotopes 238U and 235U respectively. The extremely rare element technetium can be found in uraninite in very small quantities (about 0.2 ng/kg), produced by the spontaneous fission of uranium-238.
The image at left shows well-formed crystals of uraninite. The image at right shows botryoidal uraninite. Because of the uranium decay products, both sources are gamma-ray emitters.
Shown here is a portion of the SPIRE spectrum of VY Canis Majoris (VY CMa). Credit: ESA/NASA/JPL-Caltech.
"This is one of the early spectra obtained with the SPIRE fourier transform spectrometer on Herschel. Shown here is a portion of the SPIRE spectrum of VY Canis Majoris (VY CMa), a red supergiant star near the end of its life, which is ejecting huge quantities of gas and dust into interstellar space. The inset is a SPIRE camera map of VY CMa, in which it appears as a bright compact source near the edge of a large extended cloud."
"The VY CMa spectrum is amazingly rich, with prominent features from carbon monoxide (CO) and water (H2
O). More than 200 other spectral features have been identified so far in the full spectrum, and several unidentified features are being investigated. Many of the features are due to water, showing that the star is surrounded by large quantities of hot steam. Observations like these will help to establish a detailed picture of the mass loss from stars and the complex chemistry occurring in their extended envelopes. As in all of the SPIRE spectra, the underlying emission increases towards shorter wavelengths, and is due to the emission from dust grains. The shape of the dust spectrum provides information on the properties of the dust."
"VY Canis Majoris (VY CMa) is a red supergiant star located about 4900 light years from Earth in the constellation Canis Major. It is the largest known star, with a size of 2600 solar radii, and also one of the most luminous, with a luminosity in excess of 100 000 times that of the Sun. The mass of VY CMa lies in the range 30-40 solar masses, and it has a mass-loss rate of 2 x 10-4
solar masses per year."
"The shell of gas it has ejected displays a complex structure; the circumstellar envelope is among the most remarkable chemical laboratories known in the Universe, creating a rich set of organic and inorganic molecules and dust species. Through stellar winds, these inorganic and organic compounds are injected into the interstellar medium, from which new stars orbited by new planets may form. Most of the carbon supporting life on Earth was forged by this kind of evolved star. VY CMa truly is a spectacular object, it is close to the end of its life and could explode as a supernova at any time."
This is an image obtained from muon radiography of Japan's Asama volcano. Credit: H T M Tanaka.
"TeV muons from γ ray primaries ... are rare because they are only produced by higher energy γ rays whose flux is suppressed by the decreasing flux at the source and by absorption on interstellar light."
Muon decay produces three particles, an electron
plus two neutrinos of different types.
This color picture was made by combining several exposures taken on the night of December 28th 1994 at the 0.9 m telescope of the Kitt Peak National Observatory. Credit: N.A.Sharp/NOAO/AURA/NSF.
"The Horsehead Nebula, a part of the optical nebula IC434 and also known as Barnard 33, was first recorded in 1888 on a photographic plate taken at the Harvard College Observatory. Its coincidental appearance as the profile of a horse's head and neck has led to its becoming one of the most familiar astronomical objects. It is, in fact, an extremely dense cloud projecting in front of the ionized gas that provides the pink glow so nicely revealed in this picture. We know this not only because the underside of the 'neck' is especially dark, but because it actually casts a shadow on the field to its east (below the 'muzzle')."
The Necklace Nebula glows brightly in this Nasa Hubble Space Telescope image. Credit: NASA.
"A giant cosmic necklace glows brightly in this Nasa Hubble Space Telescope image."
"The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, sun-like star."
"The nebula consists of a bright ring, measuring 12trillion miles wide, dotted with dense, bright knots of gas that resemble diamonds in a necklace."
"Newly discovered: The Necklace Nebula glows brightly in this composite image taken by the Hubble Space Telescope last month. The glow of hydrogen, oxygen, and nitrogen are shown by the colours blue, green and red respectively".
"It is located 15,000 light-years away in the constellation Sagitta."
"A pair of stars orbiting close together produced the nebula, also called PN G054.2-03.4."
"About 10,000 years ago, one of the ageing stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate. The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star’s equator, producing a ring. The embedded bright knots are dense gas clumps in the ring. The pair is so close, only a few million miles apart, that they appear as one bright dot in the centre. The stars are furiously whirling around each other, completing an orbit in a little more than a day."
This "neutrino image" of the Sun is by using the Super-Kamiokande to detect the neutrinos from nuclear fusion in the solar interior. Credit: R. Svoboda and K. Gordan (LSU).
The field of neutrino astronomy
is still very much in its infancy – the only confirmed extraterrestrial sources so far are the Sun
and supernova SN1987A. Neutrino astronomy observes astronomical objects with neutrino detectors in special observatories.
Because neutrinos are only weakly interacting with other particles of matter, neutrino detectors must be very large in order to detect a significant number of neutrinos. Neutrino detectors are often built underground to isolate the detector from cosmic rays and other background radiation.
The Super-Kamiokande, or "Super-K" is a large-scale experiment constructed in an unused mine in Japan to detect and study neutrinos. The image at right required 500 days worth of data to produce the "neutrino image" of the Sun. The image is centered on the Sun's position. This image covers a 90° x 90° octant of the sky (in right ascension and declination). The higher the brightness of the color, the larger is the neutrino flux.
The image shows the hydrogen concentrations on the Moon detected by the Lunar Prospector. Credit: NASA.
Around EeV (1018
eV) energies, there may be associated ultra high energy neutrons "observed in anisotropic clustering ... because of the relativistic neutrons boosted lifetime."
eV, [these neutrons] are flying a Mpc, with their directional arrival (or late decayed proton arrival) ... more on-line toward the source.”
From “neutron (and anti-neutron) life-lengths (while being marginal or meaningless at tens of Mpcs)", the growth of their half-lives with energy may naturally explain an associated, showering neutrino halo.
Fairly large fluxes of neutrons have been observed during solar flares
such as that of November 12, 1960, with a flux of 30-70 neutrons per cm-2
At right is the result of an all Moon survey by the Lunar Prospector using an onboard neutron spectrometer (NS). Cosmic rays impacting the lunar surface generate neutrons which in turn lose much of their energy in collisions with hydrogen atoms trapped within the Moon's surface.
Some of these thermal neutrons collide with the helium atoms within the NS to yield an energy signature which is detected and counted.
The NS aboard the Lunar Prospector has a surface resolution of 150 km.
The image shows a chain of craters on Ganymede. Credit: Galileo Project, Brown University, JPL, NASA.
Def. a hemispherical pit a basinlike opening or mouth about which a cone is often built up any large roughly circular depression or hole is called a crater.
The image at right shows a chain of 13 craters (Enki Catena) on Ganymede measuring 161.3 km in length. "The Enki craters formed across the sharp boundary between areas of bright terrain and dark terrain, delimited by a thin trough running diagonally across the center of this image. The ejecta deposit surrounding the craters appears very bright on the bright terrain. Even though all the craters formed nearly simultaneously, it is difficult to discern any ejecta deposit on the dark terrain.
This graphic shows the distance from the Oort cloud to the rest of the Solar System and two of the nearest stars measured in astronomical units (AU). The scale is logarithmic, with each specified distance ten times further out than the previous one.
An artist's rendering is of the Oort cloud and the Kuiper belt (inset). Sizes of individual objects have been exaggerated for visibility.
The Oort cloud
or the Öpik–Oort cloud
is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU
, or nearly a light-year
, from the Sun
This places the cloud at nearly a quarter of the distance to Proxima Centauri
, the nearest star
to the Sun. The outer limit of the Oort cloud defines the cosmographical
boundary of the Solar System
and the region of the Sun's gravitational dominance.
The Oort cloud is divided into two regions: a circumstellar disc-shaped inner Oort cloud (or Hills cloud) and a circumstellar envelope, spherical outer Oort cloud. Both regions lie beyond the heliosphere and in interstellar space.
, the fastest
of the interplanetary space probes currently leaving the Solar System, will reach the Oort cloud in about 300 years
and would take about 30,000 years to pass through it.
However, around 2025, the radioisotope thermoelectric generators on Voyager 1
will no longer supply enough power to operate any of its scientific instruments, preventing any further exploration by Voyager 1.
Actuators are part of the active optics of the Gran Telescopio Canarias
. Credit: Vesta
Observations at these wavelengths generally use optical components (mirrors, lenses and solid state digital detectors).
In popular culture optical astronomy encompasses a wide variety of observations via telescopes that are sensitive in the range of visible light. Scientists would call this visible-light astronomy. It includes imaging, where a picture of some sort is made of the object; photometry, where the amount of light coming from an object is measured, spectroscopy, where the distribution of that light with respect to its wavelength is measured, and polarimetry where the polarisation state of that light is measured.
Def. astronomy using infrared, visible and/or ultraviolet wavelengths is called optical astronomy.
Def. an optical system in telescopes that reduces atmospheric distortion by dynamically measuring and correcting wavefront aberrations in real time, often by using a deformable mirror is called adaptive optics.
"Already it has allowed ground-based telescopes to produce images with sharpness rivalling those from the Hubble Space Telescope. The technique is expected to revolutionize the future of ground-based optical astronomy."
The color index
is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. To measure the index, one observes the magnitude of an object successively through two different filters, such as U and B, or B and V, where U is sensitive to ultraviolet rays, B is sensitive to blue light, and V is sensitive to visible (green-yellow) light (see also: UBV system). The set of passbands or filters is called a photometric system. The difference in magnitudes found with these filters is called the U-B or B–V color index, respectively. The smaller the color index, the more blue (or hotter) the object is. Conversely, the larger the color index, the more red (or cooler) the object is. This is a consequence of the logarithmic magnitude scale, in which brighter objects have smaller (more negative) magnitudes than dimmer ones. For comparison, the yellowish Sun
has a B–V index of 0.656 ± 0.005,
while the bluish Rigel
has B–V –0.03 (its B magnitude is 0.09 and its V magnitude is 0.12, B–V = –0.03).
The passbands most optical astronomers use are the UBVRI filters, where the U, B, and V filters are as mentioned above, the R filter passes red light, and the I filter passes infrared light. These filters were specified as particular combinations of glass filters and photomultiplier tubes.
An optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum (although some work in the infrared and ultraviolet).
Cloud bands are clearly visible on Jupiter
. Credit: NASA/JPL/USGS.
"[O]range [is] the color of Jupiter"
The orange and brown coloration in the clouds of Jupiter are caused by upwelling compounds that change color when they are exposed to ultraviolet light from the Sun. The exact makeup remains uncertain, but the substances are believed to be phosphorus, sulfur or possibly hydrocarbons.
These colorful compounds, known as chromophores, mix with the warmer, lower deck of clouds. The zones are formed when rising convection cells form crystallizing ammonia that masks out these lower clouds from view.
The orange system
[in orange astronomy
] is a number of emission lines very close together forming a band in the orange portion of the visible spectrum. These lines are usually associated with particular molecular species, including ScO, YO, and TiO.
The orange band from molecular CaCl is "observed in the spectra of many carbon stars."
The Fe VII emission line at 608.7 nm, "frequently observed in the spectra of astrophysical plasmas", has been detected in planetary nebulae, Seyfert galaxies, and quasars.
The image shows the first film ever of a meteor plunging down at terminal velocity. Credit: Anders Helstrup / Dark Flight, montage, Hans Erik Foss Amundsen.
"A skydiver may have captured the first film ever of a meteorite plunging down at terminal velocity, also known as its “dark flight” stage."
"The footage was captured in 2012 by a helmet cam worn by Anders Helstrup as he and other members of the Oslo Parachute Club jumped from a small plane that took off from an airport in Hedmark, Norway."
“It can’t be anything else. The shape is typical of meteorites -- a fresh fracture surface on one side, while the other side is rounded.”
“It has never happened before that a meteorite has been filmed during dark flight; this is the first time in world history.”
"Having the rock in hand would certainly help. But despite triangulations and analyses, Helstrup and his recruits still haven’t found it."
A true color image of Ganymede is acquired by the Galileo spacecraft on June 26, 1996. Credit: PlanetUser
, NASA, JPL.
is the scientific study of planets (including Earth
), natural satellite, moons, and planetary systems, in particular those of the solar system
and the processes that form them using the radiation they emit, reflect, fluoresce, or absorb. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, originally growing from astronomy and earth science,
but which now incorporates many disciplines, including planetary astronomy, planetary geology (together with geochemistry and geophysics), atmospheric science, oceanography, hydrology
, theoretical planetary science, glaciology, and the study of extrasolar planets.
On July 19, 2012, an eruption occurred on the sun that produced a moderately powerful solar flare and a dazzling magnetic display known as coronal rain. Credit: NASA Goddard Space Flight Center, Music: 'Thunderbolt' by Lars Leonhard, courtesy of artist.
"[A] medium-strength flare erupted from the sun on July 19, 2012. The blast also generated the enormous, shimmering plasma loops, which are an example of a phenomenon known as "coronal rain," agency officials said."
"Hot plasma in the corona cooled and condensed along strong magnetic fields in the region" slowly falling back to the solar surface as plasma "rain".
A coronal cloud
is a cloud, or cloud-like, natural astronomical entity, composed of plasma and usually associated with a star or other astronomical object where the temperature is such that X-rays are emitted. While small coronal clouds are above the photosphere of many different visual spectral type stars, others occupy parts of the interstellar medium
(ISM), extending sometimes millions of kilometers into space, or thousands of light-years, depending on the size of the associated object such as a galaxy.
Observation of positrons from a terrestrial gamma ray flash is performed by the Fermi gamma ray telescope. Credit: NASA Goddard Space Flight Center.
"[P]ositron astronomy results ... have been obtained using the INTEGRAL spectrometer SPI".
The positrons are not directly observed by the INTEGRAL space telescope, but "the 511 keV positron annihilation emission is".
During solar flares “[s]everal radioactive nuclei that emit positrons are also produced; [which] slow down and annihilate in flight with the emission of two 511 keV photons or form positronium with the emission of either a three gamma continuum (each photon < 511 keV) or two 511 keV photons."
This graph displays the flux of high energy protons measured by GOES 11 over four days from November 2, 2003, to November 5, 2003. Credit: NOAA.
should be possible; it may also provide indirect information on inter-galactic magnetic fields."
Proton astronomy per se often consists of directly or indirectly detecting the protons and deconvoluting a spatial, temporal, and spectral distribution.
“[A]t the high end of the proton energy spectrum (above ≈ 1018
eV) [the Larmor radius] deflection becomes small enough that proton astronomy becomes possible.”
"The third largest solar proton event in the past thirty years took place during July 14-16, 2000, and had a significant impact on the earth's atmosphere."
This image is of asteroid 2012 LZ1 by the Arecibo Observatory in Puerto Rico using the Arecibo Planetary Radar. Credit: Arecibo Observatory.
Radar astronomy is used to detect and study astronomical objects that reflect radio rays.
"The advantages of radar in planetary astronomy result from (1) the observer's control of all the attributes of the coherent signal used to illuminate the target, especially the wave form's time/frequency modulation and polarization; (2) the ability of radar to resolve objects spatially via measurements of the distribution of echo power in time delay and Doppler frequency; (3) the pronounced degree to which delay-Doppler measurements constrain orbits and spin vectors; and (4) centimeter-to-meter wavelengths, which easily penetrate optically opaque planetary clouds and cometary comae, permit investigation of near-surface macrostructure and bulk density, and are sensitive to high concentrations of metal or, in certain situations, ice."
A lead castle is built to shield a radioactive sample. Credit: Changlc
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space.
Def. an action or process of throwing or sending out a traveling ray of energy in a line, beam, or stream of small cross section is called radiation.
Def. the shooting forth of anything from a point or surface, like the diverging rays of light is called radiation.
The term radiation is often used to refer to the ray itself.
Different types of ionizing radiation behave in different ways, so different shielding techniques are used.
This image has the radio image of Greg Taylor, NRAO, overlain on the X-ray image from Chandra. The radio source Hydra A originates in a galaxy near the center of the cluster. Optical observations show a few hundred galaxies in the cluster. Credit: NASA/CXC/SAO; Radio: NRAO.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 [Gigahertz] GHz to as low as 3 [kilohertz] kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers.
Several satellites have served as observatories for radio waves and specifically for microwaves. The Radio Astronomy Explorer (RAE) 1 is launched into orbit on July 4, 1968, around Earth, while the [Explorer 49] RAE 2 is launched on June 10, 1973, around the Moon.
The COBE is launched into Earth orbit on November 18, 1989. The WMAP is launched on June 30, 2001, into orbit at the [Lissajous orbit] Lagrange 2 location. Both satellites have aboard detectors designed to perform microwave astronomy, as these are limited to only the microwave band.
AZ Cancri. Credit: SDSS Data Release 6.
With respect to the color 'red', there are studies of the redness of objects such as the red dwarf AZ Cancri shown in the visual image at right. Cool stars of spectral class M appear red; they are (depending on their size) referred to as "red giants" or "red dwarfs".
"Ideally all intrinsic colours should be found from unreddened stars. This is possible for dwarf and giant stars later than about A0 (Johnson, 1964) ... However, it cannot be used for stars of other spectral classes since they are all relatively infrequent in space, and generally reddened."
A very important wavelength in this region is the Balmer alpha line, 656.28 nm. It is emitted or absorbed by hydrogen atoms when electrons move between the second and third electron shells. Other Balmer lines, known as beta, gamma and delta, have wavelengths of 486.13, 434.05 and 410.17 nm respectively;
these are also in the visual range but are less important than the alpha line.
This oblique astronaut photograph from the International Space Station (ISS) captures a white-to-grey ash and steam plume extending westwards from the Soufriere Hills volcano. Credit: NASA Expedition 21 crew.
Oblique images such as the one at right are taken by astronauts looking out from the International Space Station (ISS) at an angle, rather than looking straight downward toward the Earth (a perspective called a nadir view), as is common with most remotely sensed data from satellites. An oblique view gives the scene a more three-dimension quality, and provides a look at the vertical structure of the volcanic plume. While much of the island is covered in green vegetation, grey deposits that include pyroclastic flows and volcanic mud-flows (lahars) are visible extending from the volcano toward the coastline. When compared to its extent in earlier views, the volcanic debris has filled in more of the eastern coastline. Urban areas are visible in the northern and western portions of the island; they are recognizable by linear street patterns and the presence of bright building rooftops. The silver-grey appearance of the Caribbean Sea surface is due to sun-glint, which is the mirror-like reflection of sunlight off the water surface back towards the hand-held camera on-board the ISS. The sun-glint highlights surface wave patterns around the island.
Calcite fluoresces blue under short wave ultraviolet light. Credit: Herbert Art Gallery and Museum, Coventry.
Natural radiation interacts with sheared calcite to produce blue colors. Credit: Stephanie Clifford
Between 190 and 1700 nm, the ordinary refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4.
On the right is blue calcite produced by natural irradiation.
This Sin-Kamen (Blue Rock) near Lake Pleshcheyevo used to be a Meryan shrine Credit: Viktorianec.
This is a blue rock, probably various copper minerals, from the Berkeley hills near San Francisco, California. Credit: Looie496
This is an approximately natural color picture of the asteroid 243 Ida on August 28, 1993. Credit: NASA/JPL.
(Синь-Камень, in Russian literally – Blue Stone
, or Blue Rock
) is a type of pagan sacred stones, widespread in Russia, in areas historically inhabited by both Eastern Slavic (Russian), and Uralic tribes (Merya, Muroma
While in the majority of cases, the stones belonging to the Blue Stones
type, have a black, or dark gray color, this particular stone [in the image] does indeed look dark blue, when wet.
"Several types of rock surface materials can be recognized at the two sites [Viking Lander 1 and Viking Lander 2]; dark, relatively 'blue' rock surfaces are probably minimally weathered igneous rock, whereas bright rock surfaces, with a green/(blue + red) ratio higher than that of any other surface material, are interpreted as a weathering product formed in situ on the rock."
At second right is an approximately natural color image of the asteroid 243 Ida. "There are brighter areas, appearing bluish in the picture, around craters on the upper left end of Ida, around the small bright crater near the center of the asteroid, and near the upper right-hand edge (the limb). This is a combination of more reflected blue light and greater absorption of near infrared light, suggesting a difference in the abundance or composition of iron-bearing minerals in these areas."
"The [Sloan Digital Sky Survey] SDSS “blue” asteroids are related to the C-type (carbonaceous) asteroids, but not all of them are C-type. They are a mixture of C-, E-, M-, and P-types."
This is an artist's rendering of the Interstellar Boundary Explorer (IBEX) satellite. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab.
Radiation satellites may be designed and built for detection in one particular radiation astronomy or for many. Some have been built for more than one purpose or for a different purpose entirely.
To place sensors (or detectors) above the Earth’s atmosphere
is often a necessity for radiation astronomy. “The sensors at once lose the basic advantage of both radio and optical telescopes, a rigid, well-surveyed foundation upon a well-behaved earth.”
“The source locations, therefore, reflect uncertainties in both the sensor data and in vehicle aspect.”
The diagram shows scattered disc objects out to 100 AU. Credit: Eurocommuter
Scattered Disk Objects (up to 100 AU): Kuiper Belt objects are shown in grey, resonant objects within the Scattered Disk are shown in green.
The position of an object represents
- its orbit’s semi-major axis a in AU and the orbital period in years (horizontal axis)
- its orbit’s inclination i in degrees (vertical axis).
The size of the circle illustrates the object’s size relative to others. For a few large objects, the diameter drawn represents the best current estimates. For all others, the circles represent the absolute magnitude of the object.
The eccentricity of the orbit is shown indirectly by a segment extending from the left (perihelion) to the aphelion to the right. In other words, the segment illustrates the variations of the object's distance from the Sun. Objects with nearly circular orbits will show short segments while highly elliptical orbits will be represented by long segments.
Main resonances with Neptune are marked with vertical bars; 1:1 marks the position of Neptune’s orbit (and its Trojan asteroids), 2:3 marks the orbit of Pluto (and plutinos) etc.
The scattered disc (or scattered disk) is a distant region of the Solar System
that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects. The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical units (4.5 x 109
km; 2.8 x 109
mi.). While the nearest distance to the Sun approached by scattered objects is about 30–35 AU, their orbits can extend well beyond 100 AU. This makes scattered objects "among the most distant and cold objects in the Solar System".
The innermost portion of the scattered disc overlaps with a torus-shaped region of orbiting objects traditionally called the Kuiper belt,
but its outer limits reach much farther away from the Sun and farther above and below the ecliptic than the Kuiper belt proper. The literature is inconsistent in the use of the phrases "scattered disc" and "Kuiper belt"; for some, they are distinct populations; for others, the scattered disc is part of the Kuiper belt and authors may even switch between these two uses in a single publication.
Neutrons react with a number of materials through elastic scattering producing a recoiling nucleus, inelastic scattering
producing an excited nucleus, or absorption with transmutation of the resulting nucleus. Most detection approaches rely on detecting the various reaction products.
An orange sunset in the Mahim Bay is shown around the Haji Ali Dargah in India. Credit: Humayunn Peerzaada
Although the image contains a layer of cumulus clouds, at the horizon, the Atlantic Ocean meets the edge of the sky. Location: Salvador, Bahia, Brazil, July 4, 2008. Credit: Tiago Fioreze
This is a 360° view of the surrounding terrain, horizon and Martian sky, taken on November 23-28, 2005, by the Exploration Rover 'Spirit'. Credit: NASA.
A view of the horizon on the Moon's solid surface shows a black sky without stars because of sunlight coming from the left. Credit: NASA.
Seeing an orange Sun
due to atmospheric effects and feeling the warmth of its rays is probably a student's first encounter with an apparent astronomical orange radiation source.
"the expanse of space that seems to be over the earth like a dome"
is called the sky
, or sometimes the heavens
This definition applies especially well to an individual on top of the Earth's solid crust looking around at what lies above and off to the horizon in all directions. Similarly, it applies to an individual's visual view while floating on a large body of water, where off on the horizon is still water.
The image at upper right shows the horizon marking the lower edge of the sky and the upper edge of the Atlantic Ocean, with a layer of cumulus clouds just above.
A more general definition of 'sky' allows for skies as seen on other worlds. At left is a 360° panarama of the horizon on Mars as perceived in the visual true-color range of the NASA Mars Exploration Rover 'Spirit' on November 23-8, 2005.
an "expanse of space that seems to be [overhead] like a dome"
is called a sky
Even in day light, the sky may seem absent of objects if a nearby source tends to overwhelm other luminous objects.
At lower right is a view of the horizon on the Moon's solid surface taken by an Apollo 16 astronaut. The image shows a black sky without stars because the sunlight coming from the left is overwhelming.
Volcanic bombs are thrown into the sky and travel some distance before returning to the ground. This bomb is in the Craters of the Moon National Monument and Preserve, Idaho, USA. Credit: National Park Service.
Source astronomy has its origins in the actions of intelligent life on Earth when they noticed things or entities falling from above and became aware of the sky. Sometimes what they noticed is an acorn or walnut being dropped on them or thrown at them by a squirrel in a tree. Other events coupled with keen intellect allowed these life forms to deduce that some entities falling from the sky are coming down from locations higher than the tops of local trees.
a source or apparent source detected or “created
at or near the time
of the [ event
or] events” is called a primary source
Direct observation and tracking of the origination and trajectories of falling entities such as volcanic bombs presented early intelligent life with vital albeit sometimes dangerous opportunities to compose the science that led to source astronomy
"THE first suggestion that appreciable 14
C might be produced in situ
in polar ice was made by Fireman and Norris1
, who studied 14
C in CO2
extracted from both accumulation and ablation samples. In some ablation samples they observed 14
C activities between four and six times higher than those expected due to trapped atmospheric CO2
C is produced mainly by nuclear spallations of oxygen in ice. The observed concentration of 14
C in ablation ice samples is 1–3 x 103
atom per g ice, three orders of magnitude higher than expected from the amount of trapped atmospheric CO2
in this ice."
"Spallation of atmospheric oxygen nuclei might contribute up to 20% to production of 14
C produced in the atmosphere (Lal and Peters 1967)."
image is an Aitoff-Hammer equal-area map in galactic coordinates with the Galactic center in the middle of the 0.25 keV diffuse X-ray background. Credit: NASA.
A spatial distribution
is a spatial frequency
of astronomical entities, sources, or objects. A space is a volume large enough to accommodate an astronomical thing.
There is an “extensive 1/4 keV emission in the Galactic halo”, an “observed 1/4 keV [X-ray emission originating] in a Local Hot Bubble (LHB) that surrounds the Sun. ... and an isotropic extragalactic component.”
In addition to this “distribution of emission responsible for the soft X-ray diffuse background (SXRB) ... there are the distinct enhancements of supernova remnants, superbubbles, and clusters of galaxies.”
The ROSAT soft X-ray diffuse background (SXRB) image shows the general increase in intensity from the Galactic plane to the poles. At the lowest energies, 0.1 - 0.3 keV, nearly all of the observed soft X-ray background (SXRB) is thermal emission from ~106 K plasma.
A spectral distribution is often a plot or intensity, brightness, flux density, or other characteristic of a spectrum versus the spectral property such as wavelength, frequency, energy, particle speed, refractive or reflective index, for example.
The first three dozen or so astronomical X-ray objects detected other than the Sun
"represent a brightness range of about a thousandfold from the most intense source, Sco XR-1, ca.
5 x 10-10
, to the weakest sources at a few times 10-13
This is schematic of a spectrometer. Credit: Markboots
Def. a visual representation of the spectrum of a celestial body's radiation is called a spectrogram.
Def. a machine for recording spectra, producing spectrograms is called a spectrograph.
Def. an optical instrument for measuring the absorption of light by chemical substances; typically it will plot a graph of absorption versus wavelength or frequency, and the patterns produced are used to identify the substances present, and their internal structure is called a spectrometer.
Def. the measurement of the wavelength of electromagnetic radiation, especially any of several techniques used to analyze the structure of molecules; the measurement of spectra of things other than radiation, such as the masses of molecules and their breakdown products is called spectrometry.
Def. the scientific study of spectra often using spectrometers is called spectroscopy.
NASA's Spitzer Space Telescope has observed the presence of water and organic molecules in the galaxy IRAS F00183-7111. Credit: NASA/JPL-Caltech/L. Armus (SSC/Caltech), H. Kline (JPL), Digital Sky Survey
Astronomical spectroscopy is the technique of spectroscopy used in astronomy. The object of study is the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other celestial objects. Spectroscopy can be used to derive many properties of distant stars and galaxies, such as their chemical composition, but also their motion by Doppler shift measurements.
Temporal, spatial, and spectral distributions of radiation are the focus of the science of spectroscopy as applied to astronomy.
"NASA's Spitzer Space Telescope has detected the building blocks of life in the distant universe, albeit in a violent milieu. Training its powerful infrared eye on a faint object located at a distance of 3.2 billion light-years (inset [in the image on the right]), Spitzer has observed the presence of water and organic molecules in the galaxy IRAS F00183-7111. With an active galactic nucleus, this is one of the most luminous galaxies in the universe, rivaling the energy output of a quasar. Because it is heavily obscured by dust, most of its luminosity is radiated at infrared wavelengths."
"The infrared spectrograph instrument onboard Spitzer breaks light into its constituent colors, much as a prism does for visible light. The image shows a low-resolution spectrum of the galaxy obtained by the spectrograph at wavelengths between 4 and 20 microns. Spectra are graphical representations of a celestial object's unique blend of light. Characteristic patterns, or fingerprints, within the spectra allow astronomers to identify the object's chemical composition and to determine such physical properties as temperature and density."
"The broad depression in the center of the spectrum denotes the presence of silicates (chemically similar to beach sand) in the galaxy. An emission peak (red) within the bottom of the trough is the chemical signature for molecular hydrogen. The hydrocarbons (orange) are organic molecules comprised of carbon and hydrogen, two of the most common elements on Earth. Since it has taken more than three billion years for the light from the galaxy to reach Earth, it is intriguing to note the presence of organics in a distant galaxy at a time when life is thought to have started forming on our home planet."
"Additional features in the spectrum reveal the presence of water ice (blue), carbon dioxide ice (green) and carbon monoxide (purple) in both gas and solid forms. The magenta peak corresponds to singly ionized neon gas, a spectral line often used by astronomers as a diagnostic of star formation rates in distant galaxies."
This is a Hubble Space Telescope Image of NGC 4414. Credit: Hubble Heritage Team (AURA/STScI/NASA).
This is an image of Messier 31, the Andromeda galaxy from 1899. Credit: Isaac Roberts.
"In 1995, the majestic spiral galaxy NGC 4414 was imaged by the Hubble Space Telescope as part of the HST Key Project on the Extragalactic Distance Scale. [The galaxy was] observed ... on 13 different occasions over the course of two months."
"Images were obtained with Hubble's Wide Field Planetary Camera 2 (WFPC2) through three different color filters."
"Based on [...] careful brightness measurements of variable stars in NGC 4414, [...] an accurate determination of the distance to the galaxy [was made]."
"The resulting distance to NGC 4414, 19.1 megaparsecs or about 60 million light-years, along with similarly determined distances to other nearby galaxies, contributes to astronomers' overall knowledge of the rate of expansion of the universe. The Hubble constant (H0) is the ratio of how fast galaxies are moving away from us to their distance from us. This astronomical value is used to determine distances, sizes, and the intrinsic luminosities for many objects in our universe, and the age of the universe itself."
"Due to the large size of the galaxy compared to the WFPC2 detectors, only half of the galaxy observed was visible in the datasets collected by the Key Project astronomers in 1995. In 1999, the Hubble Heritage Team revisited NGC 4414 and completed its portrait by observing the other half with the same filters as were used in 1995. The end result is a stunning full-color look at the entire dusty spiral galaxy. The new Hubble picture shows that the central regions of this galaxy, as is typical of most spirals, contain primarily older, yellow and red stars. The outer spiral arms are considerably bluer due to ongoing formation of young, blue stars, the brightest of which can be seen individually at the high resolution provided by the Hubble camera. The arms are also very rich in clouds of interstellar dust, seen as dark patches and streaks silhouetted against the starlight."
Standard-candles astronomy is the astronomical effort to find, study and develop standard-candle candidates for use as standard candles.
are stars in visual astronomy
that may be used to calculate distances because their characteristics are, or appear to be, distance independent.
This is a real visual image of the red giant Mira
by the Hubble Space Telescope. Credit: Margarita Karovska (Harvard-Smithsonian Center for Astrophysics) and NASA.
“A red giant
is a luminous giant star
The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower. The appearance of the red giant is from yellow orange to red, including the spectral types
K and M, but also class S stars and most carbon stars
. The most common red giants are the so-called red giant branch stars (RGB stars). Another case of red giants are the asymptotic giant branch
stars (AGB). To the AGB stars belong the carbon stars of type C-N and late C-R. The stellar limb of a red giant is not sharply-defined, as depicted in many illustrations. Instead, due to the very low mass density of the envelope, such stars lack a well-defined photosphere
. The body of the star gradually transitions into a 'corona
' with increasing radii.
The nucleus of a helium atom, where two protons
have the same charge, but still stay together due to the strong nuclear force. Credit: Yzmo
"In field theory it is known that coupling constants “run”. This means that the values of the coupling constants that one measures depend on the energy at which the measurement is performed. [...] the three different coupling constants [one each for the strong force, electromagnetic force, and the weak force] of the standard model seem to converge to the same value at an energy scale of about 1016
GeV [...] This suggests that there is only one coupling constant at high energies and most likely only one symmetry group. [...] The current belief [is] that the electromagnetic, weak and strong forces [are] unified at about 1016
GeV [as such] one has to rely on [the] particle physics interactions which can lead to electromagnetic radiation and cosmic rays".
A mechanism is suggested for anomalous cosmic rays (ACRs) of the acceleration of pick-up ions at the solar wind termination shock. Credit: Eric R. Christian.
An "analysis of the energy-loss distributions in the GRS HEM during the impulsive phase of this event indicates that γ-rays from the decay of π0
mesons were detected [...] The production of pions, which is accompanied (on average) by neutrons, has an energy threshold of ~290 MeV for p
and ~180 MeV for p
-α interactions, giving, therefore, a lower limit to the maximum energy of the particles accelerated at the Sun."
The ALMA observations — shown here in red, pink and yellow — were tuned to detect carbon monoxide molecules. Credit: ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope.
or submillimeter astronomy
is the branch of observational astronomy
that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a few hundred micrometres and a millimetre." and "Using submillimetre observations, astronomers examine molecular clouds and dark cloud cores with a goal of clarifying the process of star formation from earliest collapse to stellar birth.
These wavelengths are sometimes called Terahertz radiation, since they have frequencies of the order of 1 THz.
"The Antennae Galaxies (also known as NGC 4038 and 4039) are a pair of distorted colliding spiral galaxies about 70 million light-years away, in the constellation of Corvus (The Crow). This view combines ALMA observations, made in two different wavelength ranges during the observatory’s early testing phase, with visible-light observations from the NASA/ESA Hubble Space Telescope."
"The Hubble image is the sharpest view of this object ever taken and serves as the ultimate benchmark in terms of resolution. ALMA observes at much longer wavelengths which makes it much harder to obtain comparably sharp images. However, when the full ALMA array is completed its vision will be up to ten times sharper than Hubble."
The two images are a top panel of Hubble Space Telescope image showing the M87 jet streaming out from the galaxy's nucleus (bright round region at far left) and a bottom panel which contains a sequence of Hubble images showing motion of something at six times the speed of light. Credit: John Biretta/NASA/ESA/Space Telecsope Science Institute.
Superluminal refers to the propagation of information or matter faster than the speed of light. Under the special theory of relativity, a particle (that has [mass in special relativity] rest mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, although special relativity does not forbid the existence of particles that travel faster than light at all times (tachyons).
On the other hand, what some physicists refer to as "apparent" or "effective" FTL
depends on the hypothesis that unusually distorted regions of spacetime might permit matter to reach distant locations in less time than light could in normal or undistorted spacetime. Although according to current theories matter is still required to travel subluminally with respect to the locally distorted spacetime region, apparent
FTL is not excluded by general relativity.
Tachyonic γ rays have not been observed directly as of 2007.
"The tachyonic spectral densities generated by ultra-relativistic electrons in uniform motion are fitted to the high-energy spectra of Galactic supernova remnants, such as RX J0852.0−4622 and the pulsar wind nebulae in G0.9+0.1 and MSH 15-52. ... Tachyonic cascade spectra are quite capable of generating the spectral curvature seen ... Estimates on the electron/proton populations generating the tachyon flux are obtained from the spectral fits"
"Tachyonic radiation implies superluminal signal transfer [1-7], the energy quanta propagating faster than light in vacuum, in contrast to rotating superluminal light sources emitting vacuum Cherenkov radiation [8, 9]."
"The existence of superluminal energy transfer has not been established so far, and one may ask why. There is the possibility that superluminal quanta just do not exist, the vacuum speed of light being the definitive upper bound. There is another explanation, the interaction of superluminal radiation with matter is very small, the quotient of tachyonic and electric fine-structure constants being q2
≈ 1.4 x 10-11
, and therefore superluminal quanta are hard to detect."
“Observed variations concerning the brightness distributions in four extragalactic radio sources were so rapid that the apparent transverse velocity of expansion is greater than the velocity of light.”
The electric vectors of PKS0521-36 show clear structure and alignment. Credit: Keel.
Synchrotron radiation is radiation produced from particles traveling along curved paths near the speed of light.
Compilation is shown of the measurements of the total extragalactic gamma-ray intensity between 1 keV and 820 GeV, with different components from current models. Credit: The e-ASTROGAM Collaboration.
"Previously, it was suggested that the [dark matter] DM consists of [weakly interacting massive particles] WIMPs that naturally emerge from the super-symmetric extension of the Standard model. Such a WIMP particle was predicted to have a mass of the order of 100 GeV. However, no such particle has been experimentally found and the search for DM candidates is now being broadened into other directions. Recently, the idea of involving a complete hidden sector of new particles was revitalized."
The Schmidt Telescope at the former Brorfelde Observatory is now used by amateur astronomers. Credit: Mogens Engelund
A radiation telescope is an instrument designed to collect and focus radiation so as to make distant sources appear nearer.
These two spectra show the proportional counting rates during the roll maneuver for GX 263 +3. Credit: H. Gursky, E. M. Kellogg, and P. Gorenstein.
A temporal distribution
is a distribution over time. Also known as a time distribution. A temporal distribution usually has the independent variable 'Time' on the abscissa
and other variables viewed approximately orthogonal to it. The time distribution can move forward in time, for example, from the present into the future, or backward in time, from the present into the past. Usually, the abscissa is plotted forward in time with the earlier time at the intersection with the ordinate
variable at left. Geologic time is often plotted on the abscissa versus phenomena on the ordinate or as a twenty-four hour clock analogy.
"An X-ray source was observed in the constellation Vela from an attitude-controlled Aerobee 150 rocket launched from the White Sands Missile Range on February 2, 1968. The object, which may be the previously reported Vel XR-1 (Chodil et al.
1967), lies close to the galactic plane; we designate it as GX263+3."
The image on the upper right "shows the counting rates plotted against time during the maneuver in which the new source was observed. The peaks labeled 1, 2, 3, anf 4 all refer to this source. Peaks 1 and 2 determine a location that is the same within experimental error as the location determined by peaks 3 and 4. The reduction in background level from 130 to 150 sec after launch occurs when a large portion of the field of view falls below the horizon."
The second image down on the right shows the most "probable celestial locations defined by the peaks in [the upper image on the right] and counting-rate ratios are shown as line segments. Separations between intersections are consistent with a single X-ray source and statistical errors in determination of times of peak counting rates. Shaded area around intersections, and enlargement, show the region of uncertainty of the source. Lines labeled 1st pass
and 2d pass
refer to the center of the field of view during scan. Area inclosed by dashed lines is the region of uncertainty [well within Vela and the Chodil polygon] of Vel XR-1 as reported by Chodil et al.
Theoretical radiation astronomy
At the bottom of this visible emission model is a visual intensity curve. Credit: Stanlekub
At its simplest theoretical radiation astronomy is the definition of terms to be applied to astronomical radiation phenomena.
Def. a theory of the science of the biological, chemical, physical, and logical laws (or principles) with respect to any natural radiation source in the sky especially at night is called theoretical radiation astronomy.
Exploratory theory is the playtime activity that leads to discoveries which better our world. In the radiation physics laboratories here on Earth, the emission, reflection, transmission, absorption, and fluorescence of radiation is studied and laws relative to sources are proven.
is a law or rule that has to be, or usually is to be followed, or can be desirably followed, or is an inevitable consequence of something, such as the laws observed in nature or the way that a system is constructed. The principles of such a system are understood by its users as the essential characteristics of the system, or reflecting system's designed purpose, and the effective operation or use of which would be impossible if any one of the principles was to be ignored.
Radiation astronomy consists of three fundamental parts:
- derivation of logical laws with respect to incoming radiation,
- natural radiation sources outside the Earth, and
- the sky and associated realms with respect to radiation.
a spontaneous emission of an α ray, β ray, or γ ray by the disintegration of an atomic nucleus is called radioactivity
This is a fission reaction. Credit: .
Polonium-214 has a half life of 163 microseconds (a microsecond is one-millionth of a second).
When this process is started artificially, it is called transmutation.
Center is an example of an artificial transmutation, this one being called a fission reaction.
This is a false-color
image of the Sun's corona
as seen in extreme ultraviolet (at 17.1 nm) by the Extreme ultraviolet Imaging Telescope aboard Stereo B. Credit: NASA.
There are many important spectral lines in these wavelengths. Among the most important are the Lyman lines, which are emitted or absorbed when an electron jumps to or from the innermost electron shell in a hydrogen atom. The first three (known as alpha, beta and gamma) have wavelengths of 121.52, 102.53 and 97.22 nm respectively.
Since the Earth's atmosphere strongly absorbs ultraviolet light, especially the shorter wavelengths, ultraviolet astronomy is mostly conducted by satellites. Longer wavelengths can be detected from baloons launched into the stratosphere.
Like the English astronomer William Fox, "In the summer of 1980, reflecting his age, Walter Scott Houston finally underwent surgery to remove a cataract from his right eye. Now to just about anyone else, a cataract would spell the end of a sky gazing career. But not Houston. With his lens removed and a plastic UV-transparent replacement implanted, Scotty reported that a whole new world of star gazing was opened up. The flood of ultraviolet light onto his retina allowed him to see faint blue stars previously invisible by at least one magnitude above the visual limit (to normally sighted observers)."
This image of Venus is taken through a violet filter by the Galileo spacecraft on February 14, 1990. Credit: NASA/JPL-Caltech.
"The aluminium abundance was derived from the resonance line at 394.4nm, and Al is underabundant by ∼ −0.7 dex with respect to iron."
"These abundances are the LTE values; no NLTE corrections, as prescribed by Baum ̈uller and Gehren (1997) and Baumüller et al. (1998), have been applied. The prescribed NLTE corrections for Teff
= 6500K, log g = 4.0, [Fe/H] = –3.0 are –0.11 ... for ... Al .... If we assume these values to apply for our lower-gravity star [CS 29497-030], then Al follows iron"
. The elemental abundance ratios for CS 29497-030 of aluminum are [Al/H] = -3.37, [Al/Fe] = -0.67.
A discovery in violet astronomy
is that "carbon stars are enormously fainter in the violet region than expected from appropriate blackbody spectra."
Violet photographs of the planet Venus taken in 1927 “recorded two nebulous bright streaks, or bands, running ... approximately at right angles to the terminator” that may be from the upper atmosphere.
"The “Purple Haze” is a diffuse blueish/purple glow within a few arcseconds of the central star in HST images of the Homunculus (Morse et al. 1998; Smith et al. 2000, 2004). This emission is seen in excess of violet starlight scattered by dust, and the strength of the excess increases into the far UV (Smith et al. 2004; hereafter Paper I)."
This image shows the 26-inch Warner & Swasey refracting telescope at the United States Naval Observatory. Credit: Waldon Fawcett.
What is “the “old-fashioned” spirit of real-time visual astronomy”?
“I think everyone can conjure up a mental image of astronomers at every level and place in history, gazing through the eyepieces of their telescopes at sights far away - true visual astronomy.”
Illustrating the red and blue shift for the observer from an exoplanet.
Doppler Shift is the basis for a Spectroscopic Binary system. It is found by either two separate shifts in spectra or a single shift generated by an unseen companion on the primary star. It is important because the shifts can be used to find the radial velocity of both stars or the visible one if only one spectrum is observed. The equation to determine radial velocity is:
c is the speed of light in a vacuum (3x108 m/s)
λ0 is the rest wavelength of the spectra
Δλ is the change from the rest wavelength to the measured wavelength
vr is the radial velocity in m/s
If the period is known this can be paired with it to determine the semi-major axis.
The diagram shows beta-minus decay from a nucleus. Credit: Inductiveload
The weak interaction
is expressed with respect to nuclear electrons and the continuous β
-ray emission spectrum of β
"The observation of a neutrino burst within 3 h of the associated optical burst from supernova 1987A in the Large Magellanic Cloud provides a new test of the weak equivalence principle, by demonstrating that neutrinos and photons follow the same trajectories in the gravitational field of the galaxy."
This image captures the core of Messier 31 (M31) in X-rays using the Chandra X-ray Observatory. Credit: S. Murray, M. Garcia, et al., Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA.
X-rays are electromagnetic radiation from a portion of the wavelength spectrum of about 5 to 8 nanometers (nm)s down to approximately 5 to 8 picometers (pm)s (ranging over three orders of magnitude).
An astronomical X-ray source may have one or more positional locations, plus associated error circles or boxes, from which incoming X-radiation (X-rays) has been detected.
Generally, a coronal cloud
, a cloud composed of plasma, is usually associated with a star or other celestial or astronomical body, extending sometimes millions of kilometers into space, or thousands of light-years, depending on the associated body. The high temperature of the coronal cloud gives it unusual spectral features. These features have been traced to highly ionized atoms of elements such as iron which indicate a plasma's temperature in excess of 106
K (MK) and associated emission of X-rays.
The importance of X-ray astronomy
is exemplified in the use of an X-ray imager such as the one on GOES 14 for the early detection of solar flares, coronal mass ejections (CME)s and other X-ray generating phenomena that impact the Earth.
This is a true-color image of Io taken by the Galileo probe. Credit: NASA.
Yellow astronomy is astronomy applied to the various extraterrestrial yellow sources of radiation, especially at night. It is also conducted above the Earth's atmosphere and at locations away from the Earth as a part of explorational (or exploratory) yellow astronomy.
There are yellow objects and emission lines in the yellow portion of the visible spectrum from 570 to 590 nm in wavelength.
is the innermost of the four Galilean moons of the planet Jupiter
and, with a diameter of 3,642 kilometres (2,263 mi), the fourth-largest moon in the Solar System
. With over 400 active volcanoes, Io is the most geologically active object in the Solar System.
Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost. Io's volcanism is responsible for many of the satellite's unique features. Its volcanic plumes and lava flows produce large surface changes and paint the surface in various shades of yellow, red, white, black, and green, largely due to allotropes and compounds of sulfur.
- ↑ Craig F. Bohren. Atmospheric Optics. http://homepages.wmich.edu/%7Ekorista/atmospheric_optics.pdf.
- ↑ Nicole P. Vogt; Martha P. Haynes; Riccardo Giovanelli; Terry Herter (June 2004). "M/L, Hα Rotation Curves, and HI Gas Measurements for 329 Nearby Cluster and Field Spirals. III. Evolution in Fundamental Galaxy Parameters". The Astronomical Journal 127 (6): 3325-37. doi:10.1086/420703. http://iopscience.iop.org/1538-3881/127/6/3325. Retrieved 2013-12-20.
- ↑ 3.0 3.1 Emily Conover (March 4, 2019). Hidden ancient neutrinos may shape the patterns of galaxies. Science News. https://www.sciencenews.org/article/hidden-ancient-neutrinos-may-shape-patterns-galaxies. Retrieved 7 March 2019.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Daniel Baumann; Florian Beutler; Raphael Flauger; Daniel Green; Anže Slosar; Mariana Vargas-Magaña; Benjamin Wallisch; Christophe Yèche (25 February 2019). "First constraint on the neutrino-induced phase shift in the spectrum of baryon acoustic oscillations". Nature Physics. doi:10.1038/s41567-019-0435-6. https://www.nature.com/articles/s41567-019-0435-6. Retrieved 7 March 2019.
- ↑ 5.0 5.1 J Abraham; P Abreu; M Aglietta; C Aguirre; D Allard; The Pierre Auger Collaboration (November 9, 2007). "Correlation of the highest-energy cosmic rays with nearby extragalactic objects". Science 318 (5852): 938-43. doi:10.1126/science.1151124. http://www.sciencemag.org/content/318/5852/938.full. Retrieved 2013-11-04.
- ↑ 6.0 6.1 Daniele Fargion (April 2010). "UHECR besides CenA: Hints of galactic sources". Progress in Particle and Nuclear Physics 64 (2): 363-5. doi:10.1016/j.ppnp.2009.12.049. http://www.sciencedirect.com/science/article/pii/S0146641009001276. Retrieved 2014-01-09.
- ↑ 7.0 7.1 7.2 7.3 Mark Fischetti (February 5, 2019). Warning Scale Unveiled for Dangerous Rivers in the Sky. Scientific American. https://www.scientificamerican.com/article/warning-scale-unveiled-for-dangerous-rivers-in-the-sky/. Retrieved 8 February 2019.
- ↑ 8.0 8.1 Martin Ralph (February 5, 2019). Warning Scale Unveiled for Dangerous Rivers in the Sky. Scientific American. https://www.scientificamerican.com/article/warning-scale-unveiled-for-dangerous-rivers-in-the-sky/. Retrieved 8 February 2019.
- ↑ Darling, David. "Alpha particle". Encyclopedia of Science. Archived from the original on 14 December 2010. https://web.archive.org/web/20101214053417/http://daviddarling.info/encyclopedia/A/alphapart.html. Retrieved 7 December 2010.
- ↑ 10.0 10.1 10.2 10.3 10.4 10.5 David R. Williams (November 2011). Lunar Prospector Neutron Spectrometer (NS). Goddard Space Flight Laboratory: National Aeronautics and Space Administration. http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1998-001A-02. Retrieved 2012-01-11.
- ↑ Karen C. Fox (May 31, 2012). Science Nugget: Catching Solar Particles Infiltrating Earth's Atmosphere. Greenbelt, Maryland: NASA Goddard Space Flight Center. http://www.nasa.gov/mission_pages/sunearth/news/particles-gle.html. Retrieved 2012-08-17.
- ↑ K. R. Schultz (September 1998). "Cost Effective Steps to Fusion power: IFE target fabrication, injection and tracking". Journal of Fusion Energy 17 (3): 237-46. doi:10.1023/A:1021814514091. http://www.springerlink.com/content/r7u527p786144l7k/. Retrieved 2012-06-08.
- ↑ L. A. Rancitelli; R. W. Perkins; W. D. Felix; N. A. Wogman (1971). "Erosion and mixing of the lunar surface from cosmogenic and primordial radio-nuclide measurements in Apollo 12 lunar samples". Proceedings of the Lunar Science Conference 2: 1757-72. http://adsabs.harvard.edu/full/1971LPSC....2.1757R. Retrieved 2012-06-08.
- ↑ 14.0 14.1 Preston, G. W.; Beers, T. C.; Shectman, S. A. (December 1993). "The Space Density and Kinematics of Metal-Poor Blue Main Sequence Stars Near the Solar Circle". Bulletin of the American Astronomical Society 25 (12): 1415.
- ↑ 15.0 15.1 Klochkova, Valentina; Ermakov, Sergey; Panchuk, Vladimir; Zhao, Gang (July 2007). Ana I. Gómez de Castro. ed. High resolution spectroscopy of halo stars within the spectral region 3550-5000 °A°A, In: UV Astronomy: Stars from Birth to Death. Proceedings of the Joint Discussion n.4 during the IAU general Assembly of 2006. International Astronomical Union. pp. 161. ISBN 978-84-7491-852-6. Bibcode: 2007uasb.conf..161K.
- ↑ Juna A. Kollmeier; Andrew Gould (July 20, 2007). "Where Are the Old-Population Hypervelocity Stars?". The Astrophysical Journal 664 (1): 343-8. doi:10.1086/518405. http://iopscience.iop.org/0004-637X/664/1/343. Retrieved 2012-03-05.
- ↑ D. Crisp; H. B. Hammel (June 14, 1995). Hubble Space Telescope Observations of Neptune. Hubble News Center. http://hubblesite.org/newscenter/archive/releases/1995/09/image/a/. Retrieved April 22, 2007.
- ↑ Kirk Munsell; Harman Smith; Samantha Harvey (November 13, 2007). Neptune overview, In: Solar System Exploration. NASA. http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=OverviewLong. Retrieved February 20, 2008.
- ↑ cumulus. San Francisco, California: Wikimedia Foundation, Inc. February 8, 2013. http://en.wiktionary.org/wiki/cumulus. Retrieved 2013-02-17.
- ↑ Baffled Scientists Say Less Sunlight Reaching Earth. LiveScience. 2006-01-24. http://www.livescience.com/environment/060124_earth_albedo.html. Retrieved 2011-08-19.
- ↑ Open Questions in Physics. German Electron-Synchrotron. A Research Centre of the Helmholtz Association. Updated March 2006 by JCB. Original by John Baez.
- ↑ J. Walker (January 4, 1994). The Oh-My-God Particle. Fourmilab. http://www.fourmilab.ch/documents/OhMyGodParticle/.
- ↑ Jonathan I. Lunine (1993). "The Atmospheres of Uranus and Neptune". Annual Review of Astronomy and Astrophysics 31: 217–263. doi:10.1146/annurev.aa.31.090193.001245.
- ↑ 24.0 24.1 Wolfhard Schlosser; Rita Schulz; Paul Koczet (1986). The cyan shells of Comet P/Halley, In: Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 3. European Space Agency. pp. 495-8. Bibcode: 1986ESASP.250c.495S.
- ↑ James A. Phillips (2009). Green Comet Approaches Earth. National Aeronautics and Space Administration Science News. http://science.nasa.gov/science-news/science-at-nasa/2009/04feb_greencomet/. Retrieved 2012-05-05.
- ↑ 26.0 26.1 JamesR1701E~enwiktionary (4 August 2004). "distribution". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 23 December 2019.
- ↑ 27.0 27.1 27.2 27.3 27.4 Henric S. Krawczynski; Ira Jung; Jeremy S. Perkins; Arnold Burger; Michael Groza (October 21, 2004). Thick CZT Detectors for Space-Borne X-ray Astronomy, In: Hard X-Ray and Gamma-Ray Detector Physics VI, 1. 5540. Denver, Colorado USA: The International Society for Optical Engineering. pp. 13. doi:10.1117/12.558912. http://arxiv.org/pdf/astro-ph/0410077. Retrieved 2013-05-20.
- ↑ 28.0 28.1 28.2 J. Singleton; A. Ardavan; H. Ardavan; J. Fopma; D. Halliday (2005). Non-spherically-decaying radiation from an oscillating superluminal polarization current: possible low-power, deep-space communication applications in the MHz and THz bands, 16th International Symposium on Space Terahertz Technology. pp. 117. http://www.nrao.edu/meetings/isstt/papers/2005/2005117000.pdf. Retrieved 2014-03-18.
- ↑ Bill Keel (October 2003). Jets, Superluminal Motion, and Gamma-Ray Bursts. Tucson, Arizona USA: University of Arizona. http://www.astr.ua.edu/keel/galaxies/jets.html. Retrieved 2014-03-19.
- ↑ Deharveng (November 11, 2008). Glowing Stellar Nurseries. European Southern Observatory. http://www.eso.org/public/images/eso0840a/. Retrieved 2014-03-13.
- ↑ APS. Physics Subject Headings. College Park, MD: American Physical Society. https://physh.aps.org/concepts/893ecc24-c678-4687-bd3a-0b4a1bcb4cfc. Retrieved 2018-01-08.
- ↑ S. Wolpert (July 24, 2008). Scientists solve 30-year-old aurora borealis mystery. University of California. http://www.universityofcalifornia.edu/news/article/18277. Retrieved 2008-10-11.
- ↑ 33.0 33.1 33.2 33.3 33.4 H. S. Hudson; A. B. Galvin (September 1997). A. Wilson. ed. Correlated Studies at Activity Maximum: the Sun and the Solar Wind, In: Correlated Phenomena at the Sun, in the Heliosphere and in Geospace. Noordwijk, The Netherlands: European Space Agency. pp. 275-82. ISBN 92-9092-660-0. Bibcode: 1997ESASP.415..275H.
- ↑ 34.0 34.1 T. H. Burnett et al.; The JACEE Collaboration (January 1990). "Energy spectra of cosmic rays above 1 TeV per nucleon". The Astrophysical Journal 349 (1): L25-8. doi:10.1086/185642. http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990ApJ...349L..25B&link_type=GIF&db_key=AST. Retrieved 2011-11-25.
- ↑ Adolf N. Witt; Karl D. Gordon; Douglas G. Furton (July 1, 1998). "Silicon Nanoparticles: Source of Extended Red Emission?". The Astrophysical Journal Letters 501 (1): L111-5. doi:10.1086/311453. http://iopscience.iop.org/1538-4357/501/1/L111. Retrieved 2013-07-30.
- ↑ A. Finoguenov; M.G. Watson; M. Tanaka; C.Simpson; M. Cirasuolo; J.S. Dunlop; J.A. Peacock; D. Farrah et al. (April 2010). "X-ray groups and clusters of galaxies in the Subaru-XMM Deep Field". Monthly Notices of the Royal Astronomical Society 403 (4): 2063-76. doi:10.1111/j.1365-2966.2010.16256.x. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2010.16256.x/full. Retrieved 2011-12-09.
- ↑ Reuters (February 15, 2013). Meteorite hits central Russia, more than 500 people hurt. Chelyabinsk, Russia: Yahoo! News. http://news.yahoo.com/photos/trail-falling-object-seen-above-urals-city-chelyabinsk-photo-101834569.html. Retrieved 2013-02-15.
- ↑ Sparke & Gallagher III 2000, p. i
- ↑ Hupp, E.; Roy, S.; Watzke, M. (August 12, 2006). "NASA Finds Direct Proof of Dark Matter". NASA. Retrieved April 17, 2007.
- ↑ Uson, J. M.; Boughn, S. P.; Kuhn, J. R. (1990). "The central galaxy in Abell 2029 – An old supergiant". Science 250 (4980): 539–540. doi:10.1126/science.250.4980.539. PMID 17751483.
Hoover, A. (June 16, 2003). "UF Astronomers: Universe Slightly Simpler Than Expected". Hubble News Desk. Archived from the original on July 20, 2011. Retrieved March 4, 2011. Based upon:
Graham, A. W.; Guzman, R. (2003). "HST Photometry of Dwarf Elliptical Galaxies in Coma, and an Explanation for the Alleged Structural Dichotomy between Dwarf and Bright Elliptical Galaxies". The Astronomical Journal 125
(6): 2936–2950. doi:10.1086/374992
- ↑ Jarrett, T. H. "Near-Infrared Galaxy Morphology Atlas". California Institute of Technology. Retrieved January 9, 2007.
- ↑ Gott III, J. R. (2005). "A Map of the Universe". The Astrophysical Journal 624 (2): 463–484. doi:10.1086/428890.
- ↑ Christopher J. Conselice et al. (2016). "The Evolution of Galaxy Number Density at z < 8 and its Implications". The Astrophysical Journal 830 (2): 83. doi:10.3847/0004-637X/830/2/83.
- ↑ Fountain, Henry (17 October 2016). "Two Trillion Galaxies, at the Very Least". The New York Times. Retrieved 17 October 2016.
- ↑ Mackie, Glen (1 February 2002). "To see the Universe in a Grain of Taranaki Sand". Centre for Astrophysics and Supercomputing. Retrieved 28 January 2017.
- ↑ Richard Powell (30 July 2006). The Universe within 1 billion Light Years The Neighbouring Superclusters. Atlas of the Universe. http://www.atlasoftheuniverse.com/superc.html. Retrieved 2018-04-01.
- ↑ Vedrenne G; Atteia J.-L. (2009). Gamma-Ray Bursts: The brightest explosions in the Universe. Springer/Praxis Books. ISBN 978-3-540-39085-5. http://books.google.com/?id=jZHSdrvzz0gC&printsec=frontcover#v=onepage&q&f=false.
- ↑ 49.0 49.1 49.2 49.3 49.4 K. Dennerl (November 7, 2002). Mars: Mars Glows in X-rays. Boston, Massachusetts, USA: NASA, Harvard University. http://chandra.harvard.edu/photo/2002/mars/. Retrieved 2012-11-26.
- ↑ A. Einstein; N. Rosen (January 1937). "On gravitational waves". Journal of the Franklin Institute 223 (1): 43-54. doi:10.1016/S0016-0032(37)90583-0. http://www.sciencedirect.com/science/article/pii/S0016003237905830?via%3Dihub. Retrieved 2018-1-03.
- ↑ Ivy F. Kupec (11 February 2016). Gravitational waves detected 100 years after Einstein's prediction. Alexandria, Virginia, USA: National Science Foundation. pp. 1. https://www.nsf.gov/news/news_summ.jsp?cntn_id=137628. Retrieved 2018-01-03.
- ↑ Davide Castelvecchi; Alexandra Witze (11 February 2016). "Einstein's gravitational waves found at last LIGO 'hears' space-time ripples produced by black-hole collision". Nature. doi:10.1038/nature.2016.19361. http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361. Retrieved 2018-1-03.
- ↑ B. P. Abbott; the LIGO Scientific Collaboration]]; the Virgo Collaboration (16 October 2017). "GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral". Physical Review Letters 119 (16). doi:10.1103/PhysRevLett.119.161101.
- ↑ Constantin Sandu; Dan Brasoveanu. Sonic Electromagnetic Gravitational Spacecraft, Part - Principles, In: AIAA SPACE 2007 Conference & Exposition. 6203. American Institute of Aeronautics and Astronautics. https://arc.aiaa.org/doi/abs/10.2514/6.2007-6203. Retrieved 2018-01-10.
- ↑ 55.0 55.1 Roberto Gómez; Sascha Husa; Luis Lehner; Jeffrey Winicour (15 September 2002). "Gravitational waves from a fissioning white hole". Physical Review D 66 (6): 1-9. doi:10.1103/PhysRevD.66.064019. https://arxiv.org/pdf/gr-qc/0205038. Retrieved 2018-01-10.
- ↑ Nelson Christensen; Renate Meyer; Adam Libson (1 December 2003). "A Metropolis–Hastings routine for estimating parameters from compact binary inspiral events with laser interferometric gravitational radiation data". Classical and Quantum Gravity 21 (1): 317-330. doi:10.1088/0264-9381/21/1/023. http://people.carleton.edu/~nchriste/CQG03.pdf. Retrieved 2018-01-19.
- ↑ John G. Phillips; Sumner P. Davis; Bo Lindgren; Walter J. Balfour (December 1987). "The near-infrared spectrum of the FeH molecule". The Astrophysical Journal Supplement Series 65 (12): 721-78. doi:10.1086/191241.
- ↑ 58.0 58.1 58.2 58.3 I. Bertini; N. Thomas; C. Barbieri (January 2007). "Modeling of the light scattering properties of cometary dust using fractal aggregates". Astronomy & Astrophysics 461 (1): 351-64. doi:10.1051/0004-6361:20065461. http://www.aanda.org/articles/aa/full/2007/01/aa5461-06/aa5461-06.html. Retrieved 2011-12-08.
- ↑ The building blocks of planets within the `terrestrial' region of protoplanetary disks. nottingham.ac.uk. http://ukads.nottingham.ac.uk/cgi-bin/nph-bib_query?bibcode=2004Natur.432..479V&db_key=AST. Retrieved 2008-03-04.
- ↑ 60.0 60.1 M. Gregg (3 March 2005). "The Impending Destruction of NGC 1427A". Baltimore, Maryland USA: Hubblesite.org. Retrieved 2016-11-05.
- ↑ GS Hawkins (1966). Stonehenge Decoded. ISBN 978-0880291477.
- ↑ Alan Stern; Colwell, Joshua E. (1997). "Collisional Erosion in the Primordial Edgeworth-Kuiper Belt and the Generation of the 30–50 AU Kuiper Gap". The Astrophysical Journal 490 (2): 879–882. doi:10.1086/304912.
- ↑ Jane Luu; David Jewitt (November 1996). "Color Diversity among the Centaurs and Kuiper Belt Objects". The Astronomical Journal 112 (5): 2310-8. http://adsabs.harvard.edu/full/1996AJ....112.2310L. Retrieved 2013-11-05.
- ↑ The MPC Orbit (MPCORB) Database. http://www.cfa.harvard.edu/iau/MPCORB.html.
- ↑ Carl D. Murray; Stanley F. Dermott (1999). Solar System Dynamics. Cambridge University Press. ISBN 0 521 57295 9.
- ↑ 66.0 66.1 Carlos Miralles (AeroVironment); Tom Nelson (FMA) (25 June 2019). "SEVERE WEATHER 101 Lightning Types". NSSL, NOAA. Retrieved 25 June 2019.
- ↑ 67.0 67.1 67.2 Mark R. Mireles; Kirth L. Pederson; Charles H. Elford (February 21, 2007). Meteorologial Techniques. Offutt Air Force Base, Nebraska, USA: Air Force Weather Agency/DNT. http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA466107. Retrieved 2013-02-17.
- ↑ PJ Ozer (1995). Fantechi, R.. ed. Lithometeors in relation with desertification in the Sahelian area of Niger, In: Desertification in a European context: physical and socio-economic aspects. Luxembourg: Office for Official Publications of the European Community. pp. 567-74. ISBN 92-827-4163-X. http://www.cabdirect.org/abstracts/19971901329.html. Retrieved 2013-02-17.
- ↑ Jian-qiao Yu; Xia1 Wang; Li Wen; Jing-shun Wang (April 2008). "Studies on Correlation of Heavy Metal Pollution in Soil, Lithometeor". Journal of Agricultural Science and Technology (04). http://en.cnki.com.cn/Article_en/CJFDTOTAL-NKDB200804025.htm. Retrieved 2013-02-17.
- ↑ P. Ozer (1998). G. Demaree. ed. Lithometeors and wind velocity in relation with desertification during the dry season from 1951 to 1994 in Niger, In: International Conference on tropical climatology, meteorology and hydrology in memoriam Franz Bultot. Bruxelles (Belgium): Royal Meteorological Institute of Belgium; Royal Academy of Overseas Sciences. pp. 212-27. http://agris.fao.org/agris-search/search/display.do?f=1999/BE/BE99007.xml;BE1999001164#. Retrieved 2013-02-17.
- ↑ Peter M. Millman (1961). "A report on meteor terminology". JRASC 55: 265–267.
- ↑ Glossary International Meteor Organization. Imo.net. 2008-11-18. http://www.imo.net/glossary. Retrieved 2011-09-16.
- ↑ Diagram 2: the orbit of the Peekskill meteorite along with the orbits derived for several other meteorite falls. Uregina.ca. http://uregina.ca/~astro/mb_5.html. Retrieved 2011-09-16.
- ↑ Noyster (7 September 2017). "List of meteor showers". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 29 June 2019.
- ↑ Meteor Data Centre, IAU
- ↑ Pozar, David M. (1993). Microwave Engineering Addison-Wesley Publishing Company. ISBN 0-201-50418-9.
- ↑ http://www.google.com/search?hl=en&defl=en&q=define:microwave&ei=e6CMSsWUI5OHmQee2si1DQ&sa=X&oi=glossary_definition&ct=title
- ↑ 78.0 78.1 78.2 78.3 M. Groenewegen (November 27, 2009). SPIRE spectrum of VY Canis Majoris. Pasadena, California USA: Caltech. http://www.herschel.caltech.edu/image/nhsc2009-021a. Retrieved 2014-03-12.
- ↑ Francis Halzen; Todor Stanev; Gaurang B. Yodh (April 1, 1997). "γ ray astronomy with muons". Physical Review D Particles, Fields, Gravitation, and Cosmology 55 (7): 4475-9. doi:10.1103/PhysRevD.55.4475. http://prd.aps.org/abstract/PRD/v55/i7/p4475_1. Retrieved 2013-01-18.
- ↑ N. A. Sharp (28 December 1994). The Horsehead Nebula. Kitt Peak, Arizona USA: National Optical Astronomy Observatory (NOAO). https://www.noao.edu/image_gallery/html/im0057.html. Retrieved 2015-09-25.
- ↑ 81.0 81.1 81.2 81.3 81.4 81.5 81.6 DAILY MAIL REPORTER (12 August 2011). Giant Necklace Nebula brightly glows with dense knots of blue, green and red gases. United Kingdom: Daily Mail. http://www.dailymail.co.uk/sciencetech/article-2025275/Necklace-Nebula-brightly-glows-dense-knots-blue-green-red-gases.html. Retrieved 24 February 2014.
- ↑ KENNETH CHANG (April 26, 2005). Tiny, Plentiful and Really Hard to Catch, In: The New York Times. http://www.nytimes.com/2005/04/26/science/26neut.html?pagewanted=print&position=. Retrieved 2011-06-16. "In 1987, astronomers counted 19 neutrinos from an explosion of a star in the nearby Large Magellanic Cloud, 19 out of the billion trillion trillion trillion trillion neutrinos that flew from the supernova."
- ↑ 83.0 83.1 83.2 Fargion D; Khlopov M; Konoplich R; De Sanctis Lucentini PG; De Santis M; Mele B (March 2003). "Ultra High Energy Particle Astronomy, Neutrino Masses and Tau Airshowers". Recent Research and Development in Astrophysics 1 (3): 395-454. http://arxiv.org/pdf/astro-ph/0303233.
- ↑ Lingenfelter RE; Flamm EJ; Canfield EH; Kellman S (September 1965). "High-Energy Solar Neutrons 2. Flux at the Earth". Journal of Geophysical Research 70 (17): 4087–95. doi:10.1029/JZ070i017p04087.
- ↑ Fred Lawrence Whipple; G. Turner; J. A. M. McDonnell; M. K. Wallis (1987-09-30). "A Review of Cometary Sciences". Philosophical Transactions of the Royal Society A (Royal Society Publishing) 323 (1572): 339–347 . doi:10.1098/rsta.1987.0090. http://rsta.royalsocietypublishing.org/content/323/1572/339.short.
- ↑ Alessandro Morbidelli (2006). Origin and dynamical evolution of comets and their reservoirs of water ammonia and methane.. https://arxiv.org/abs/astro-ph/0512256.
- ↑ Kuiper Belt & Oort Cloud. NASA. http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs&Display=OverviewLong. Retrieved 2011-08-08.
- ↑ Alessandro Morbidelli (2006). "Origin and dynamical evolution of comets and their reservoirs of water ammonia and methane". arXiv:astro-ph/0512256.
- ↑ 89.0 89.1 "Catalog Page for PIA17046". Photo Journal. NASA. Retrieved April 27, 2014.
- ↑ "New Horizons Salutes Voyager". New Horizons. August 17, 2006. Archived from the original on March 9, 2011. Retrieved November 3, 2009.
- ↑ Clark, Stuart (September 13, 2013). "Voyager 1 leaving solar system matches feats of great human explorers". The Guardian.
- ↑ "Voyagers are leaving the Solar System". Space Today. 2011. Retrieved May 29, 2014.
- ↑ "It's Official: Voyager 1 Is Now In Interstellar Space". UniverseToday. 2013-09-12. Retrieved April 27, 2014.
- ↑ Ghose, Tia (September 13, 2013). "Voyager 1 Really Is In Interstellar Space: How NASA Knows". Space.com. TechMedia Network. Retrieved September 14, 2013.
- ↑ Cook, J.-R (September 12, 2013). "How Do We Know When Voyager Reaches Interstellar Space?". NASA / Jet Propulsion Lab. Retrieved September 15, 2013.
- ↑ François Roddier, ed (1999). Adaptive Optics in Astronomy. Cambridge, United Kingdom: Cambridge University Press. pp. 411. ISBN 0 521 55375 X. http://catdir.loc.gov/catdir/samples/cam031/00500597.pdf. Retrieved 2012-02-15.
- ↑ David F. Gray (1992), The Inferred Color Index of the Sun, Publications of the Astronomical Society of the Pacific, vol. 104, no. 681, pp. 1035-1038 (November 1992)
- ↑ The Simbad Astronomical Database' Rigel page
- ↑ Barrie William Jones. The search for life continued: planets around other stars. p. 111. http://books.google.com/books?id=5wX9aHqfBS0C&pg=PA111&lr=&cd=55#v=onepage&f=false.
- ↑ Faber Birren (Summer 1983). "Color and human response". Color Research and Application 8 (2): 75-81. doi:10.1002/col.5080080204. http://onlinelibrary.wiley.com/doi/10.1002/col.5080080204/abstract. Retrieved 2012-04-23.
- ↑ Elkins-Tanton, Linda T. (2006). Jupiter and Saturn. New York: Chelsea House. ISBN 0-8160-5196-8.
- ↑ Strycker, P. D.; Chanover, N.; Sussman, M.; Simon-Miller, A. (2006). A Spectroscopic Search for Jupiter's Chromophores, In: DPS meeting #38, #11.15. American Astronomical Society. Bibcode: 2006DPS....38.1115S.
- ↑ Gierasch, Peter J.; Nicholson, Philip D. (2004). Jupiter. World Book @ NASA. http://www.nasa.gov/worldbook/jupiter_worldbook.html. Retrieved 2006-08-10.
- ↑ G. H. Herbig (March 1974). "VY Canis Majoris. IV. The emission bands of ScO". The Astrophysical Journal 188 (3): 533-8. doi:10.1086/152744.
- ↑ J. E. Littleton; Sumner P. Davis (October 1988). "Transition strength data for the orange and red bands of CaCl". The Astrophysical Journal 333 (10): 1026-34. doi:10.1086/166809.
- ↑ F. P. Keenan; P. H. Norrington (July 1987). "Relative emission line strengths for Fe VII in astrophysical plasmas". Astronomy and Astrophysics 181 (2): 370-2.
- ↑ 107.0 107.1 107.2 Janet Fang (April 4, 2014). Skydiver Almost Hit by Meteorite. IFLScience. http://www.iflscience.com/space/skydiver-almost-hit-meteorite. Retrieved 2014-08-31.
- ↑ 108.0 108.1 Hans Erik Foss Amundsen (April 4, 2014). Skydiver Almost Hit by Meteorite. IFLScience. http://www.iflscience.com/space/skydiver-almost-hit-meteorite. Retrieved 2014-08-31.
- ↑ 109.0 109.1 Stuart Ross Taylor (29 July 2004). "Why can't planets be like stars?". Nature 430 (6999): 509. doi:10.1038/430509a. PMID 15282586. http://www.nature.com/nature/journal/v430/n6999/full/430509a.html.
- ↑ 110.0 110.1 Mike Wall (February 21, 2013). Super-Hot Plasma 'Rain' Falls on Sun in Amazing Video. Yahoo! News. http://news.yahoo.com/super-hot-plasma-rain-falls-sun-amazing-video-190147271.html. Retrieved 2013-02-23.
- ↑ P.A.Milne; J.D.Kurfess; R.L.Kinzer; M.D.Leising; D.D.Dixon (April 2000). Investigations of positron annihilation radiation, In: Proceedings of the 5th COMPTON Symposium. 510. Washington, DC: American Institute of Physics. pp. 21-30. doi:10.1063/1.1303167. Bibcode: 2000AIPC..510...21M. http://arxiv.org/pdf/astro-ph/9911184. Retrieved 2011-11-25.
- ↑ 112.0 112.1 G. Weidenspointner; G.K. Skinner; P. Jean; J. Knödlseder; P. von Ballmoos; R. Diehl; A. Strong; B. Cordier et al. (October 2008). "Positron astronomy with SPI/INTEGRAL". New Astronomy Reviews 52 (7-10): 454-6. doi:10.1016/j.newar.2008.06.019. http://www.sciencedirect.com/science/article/pii/S1387647308001164. Retrieved 2011-11-25.
- ↑ Gerald H. Share; Ronald J. Murphy (January 2004). Andrea K. Dupree. ed. Solar Gamma-Ray Line Spectroscopy – Physics of a Flaring Star, In: Stars as Suns: Activity, Evolution and Planets. San Francisco, CA: Astronomical Society of the Pacific. pp. 133-44. ISBN 158381163X. Bibcode: 2004IAUS..219..133S. http://heseweb.nrl.navy.mil/gamma/solar/papers/share_iau_04.pdf. Retrieved 2012-03-15.
- ↑ Francis Halzen; Dan Hooper (July 2002). "High-energy neutrino astronomy: the cosmic ray connection". Reports on Progress in Physics 65 (7): 1025-78. doi:10.1088/0034-4885/65/7/201. http://arxiv.org/pdf/astro-ph/0204527. Retrieved 2011-11-24.
- ↑ K. D. Hoffman (May 12, 2009). "High energy neutrino telescopes". New Journal of Physics11 (5): 055006. doi:10.1088/1367-2630/11/5/055006. http://arxiv.org/pdf/astro-ph/0204527. Retrieved 2012-03-28.
- ↑ Charles H. Jackman; Richard D. McPeters; Gordon J. Labow; Eric L.Fleming; Cid J. Praderas; James M. Russell (August 2001). "Northern Hemisphere atmospheric effects due to the July 2000 solar proton event". Geophysical Research Letters 28 (15): 2883-6. http://cdaw.gsfc.nasa.gov/meetings/2009_gle/data/Jackman/Jackman_2001.pdf. Retrieved 2011-11-24.
- ↑ Steven J. Ostro (October-December 1993). "Planetary radar astronomy". Reviews of Modern Physics 65 (4): 1235-79. doi:10.1103/RevModPhys.65.1235. http://rmp.aps.org/abstract/RMP/v65/i4/p1235_1. Retrieved 2012-02-09.
- ↑ M. Pim FitzGerald (February 1970). "The Intrinsic Colours of Stars and Two-Colour Reddening Lines". Astronomy and Astrophysics 4 (2): 234-43.
- ↑ D.W. Thompson (1998). "Determination of optical anisotropy in calcite from ultraviolet to mid-infrared by generalized ellipsometry". Thin Solid Films 313–4 (1-2): 341–6. doi:10.1016/S0040-6090(97)00843-2.
- ↑ И.Д. Маланин. Материалы разведки Синих камней Подмосковья в 2003 году // Краеведение и регионоведение. Межвузовский сборник научных трудов. ч.1. Владимир, 2004. (Russian)
- ↑ Бердников, В. Синий камень Плещеева озера // Наука и жизнь. – 1985. – № 1. – С. 134–139. (Russian)
- ↑ Edwin L. Strickland III (March 19, 1979). Martian soil stratigraphy and rock coatings observed in color-enhanced Viking Lander images, In: Lunar and Planetary Science Conference Proceedings. 3. New York: Pergamon Press, Inc.. pp. 3055-77. Bibcode: 1979LPSC...10.3055S. http://adsabs.harvard.edu/abs/1979LPSC...10.3055S. Retrieved 2013-05-31.
- ↑ Sue Lavoie (January 29, 1996). PIA00069: Ida and Dactyl in Enhanced Color. Pasadena, California USA: NASA/JPL. http://photojournal.jpl.nasa.gov/catalog/?IDNumber=PIA00069. Retrieved 2013-06-01.
- ↑ F Yoshida, T Nakamura (June 2007). "Subaru main belt asteroid survey (SMBAS)—size and color distributions of small main-belt asteroids". Planetary and Space Science 55 (9): 1113-25. doi:10.1016/j.pss.2006.11.016. http://www.sciencedirect.com/science/article/pii/S0032063306003357. Retrieved 2013-06-01.
- ↑ 125.0 125.1 Gerald A. Ouellette (June 1967). "Development of a Catalogue of Galactic X-Ray Sources". The Astronomical Journal 72 (5): 597-600. doi:10.1086/110278.
- ↑ Maggie Masetti. (2007). Cosmic Distance Scales – The Solar System. Website of NASA's High Energy Astrophysics Science Archive Research Center. Retrieved 2008 07-12.
- ↑ Morbidelli, Alessandro (2005). "Origin and dynamical evolution of comets and their reservoirs". arXiv:astro-ph/0512256.
- ↑ McFadden, Weissman, & Johnson (2007). Encyclopedia of the Solar System, footnote p. 584
- ↑ 129.0 129.1 129.2 Philip B. Gove, ed (1963). Webster's Seventh New Collegiate Dictionary. Springfield, Massachusetts: G. & C. Merriam Company. pp. 1221.
- ↑ 130.0 130.1 D Lal; AJT Jull; DJ Donahue; D Burtner; K Nishiizumi (1990). "Polar ice ablation rates measured using in situ cosmogenic 14
C". Nature 346: 350-352. doi:10.1038/346350a0. https://www.nature.com/articles/346350a0. Retrieved 2017-12-05.
- ↑ D Lal; A J T Jull (2001). "In-situ cosmogenic 14
C: Production and examples of its unique applications in studies of terrestrial and extraterrestrial processes". Radiocarbon 43 (28): 731-742. https://journals.uair.arizona.edu/index.php/radiocarbon/article/download/3905/3330. Retrieved 2017-12-06.
- ↑ 132.0 132.1 S. L. Snowden; R. Egger; D. P. Finkbiner; M. J. Freyberg; P. P. Plucinsky (February 1, 1998). "Progress on Establishing the Spatial Distribution of Material Responsible for the 1/4 keV Soft X-Ray Diffuse Background Local and Halo Components". The Astrophysical Journal493 (1): 715-29. doi:10.1086/305135. http://iopscience.iop.org/0004-637X/493/2/715/fulltext/. Retrieved 2012-06-14.
- ↑ Friedman H (November 1969). "Cosmic X-ray observations". Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences 313 (1514): 301-15. http://www.jstor.org/pss/2416439. Retrieved 2011-11-25.
- ↑ 134.0 134.1 134.2 134.3 Lee Armus; James Houck; Vassilis Charmandaris; Henrik Spoon; Harry Teplitz; Daniel Devost; Patrick Morris; Phil Appleton et al. (18 December 2003). Galaxy IRAS F00183-7111. Pasadena, California USA: Caltech. http://www.spitzer.caltech.edu/images/1098-ssc2003-06h-Galaxy-IRAS-F00183-7111. Retrieved 2017-05-25.
- ↑ 135.0 135.1 135.2 135.3 135.4 Wendy Freedman (1999). MAGNIFICENT DETAILS IN A DUSTY SPIRAL GALAXY. Greenbelt, Maryland USA: NASA Goddard Space Flight Center. http://nssdc.gsfc.nasa.gov/photo_gallery/caption/hst_ngc4414_9925.txt. Retrieved 2014-10-28.
- ↑ orange sphere of the sun
- ↑ Tanmay Vachaspati (1998). "Topological defects in the cosmos and lab". Contemporary Physics39 (4): 225-37. doi:10.1080/001075198181928. http://www.tandfonline.com/doi/abs/10.1080/001075198181928. Retrieved 2013-11-05.
- ↑ E. L. Chupp; H. Debrunner; E. Flueckiger; D. J. Forrest; F. Golliez; G. Kanbach; W. T. Vestrand; J. Cooper et al. (July 15, 1987). "Solar neutron emissivity during the large flare on 1982 June 3". The Astrophysical Journal 318 (7): 913-25. doi:10.1086/165423. http://adsabs.harvard.edu/abs/1987ApJ...318..913C. Retrieved 2014-04-08.
- ↑ 139.0 139.1 eso1137a (October 3, 2011). Antennae Galaxies composite of ALMA and Hubble observations. Parana, Chile: European Southern Observatory. http://www.eso.org/public/images/eso1137a/. Retrieved 2014-03-13.
- ↑ Gonzalez-Diaz, P. F. (2000). "Warp drive space-time". Physical Review D 62 (4): 044005. doi:10.1103/PhysRevD.62.044005. http://omnis.if.ufrj.br/~mbr/warp/etc/PRD62_44005.pdf.
- ↑ F. Loup; David Waite; E. Halerewicz Jr. (2001). [ttp://arxiv.org/abs/gr-qc/0107097 Reduced Total Energy Requirements for a Modified Alcubierre Warp Drive Spacetime]. ttp://arxiv.org/abs/gr-qc/0107097.
- ↑ Visser, M.; Bassett, B.; Liberati, S. (2000). "Superluminal censorship". Nuclear Physics B: Proceedings Supplement 88: 267–270. doi:10.1016/S0920-5632(00)00782-9.
- ↑ Visser, M.; Bassett, B.; Liberati, S. (1999). "Perturbative superluminal censorship and the null energy condition". AIP Conference Proceedings 493: 301–305. doi:10.1063/1.1301601. ISBN 1-56396-905-X.
- ↑ 144.0 144.1 Roman Tomaschitz (March 2007). "Superluminal cascade spectra of TeV [gamma-ray sources"]. Annals of Physics 322 (3): 677-700. doi:10.1016/j.aop.2006.11.005. http://wallpaintings.at/geminga/superluminal_cascade_spectra_TeV_gamma-ray_sources.pdf. Retrieved 2011-11-24.
- ↑ 145.0 145.1 R Tomaschitz (October 2010). "Superluminal spectral densities of ultra-relativistic electrons in intense electromagnetic wave fields". Applied Physics B Lasers and Optics 101 (1-2): 143-64. doi:10.1007/s00340-010-4182-8. http://wallpaintings.at/geminga/superluminal_spectral_densities_ultra-relativistic_electrons_electromagnetic_wave_fields.pdf. Retrieved 2012-03-21.
- ↑ M. H. Cohen; K. I. Kellermann; D. B. Shaffer; R. P. Linfield; A. T. Moffet; J. D. Romney; G. A. Seielstad; I. I. K. Pauliny-Toth et al. (August 1977). "Radio sources with superluminal velocities". Nature 268: 405-9. doi:10.1038/268405a0.
- ↑ G. Vankova-Kirilova; V. Bozhilov; V. Kozhuharov; S. Lalkovski (2017). "All-sky mapping in the 100 MeV region in search for point-like dark matter sources". arxiv: 112. https://arxiv.org/pdf/1711.01265#page=106. Retrieved 2018-4-04.
- ↑ 148.0 148.1 148.2 H. Gursky; E. M. Kellogg; P. Gorenstein (November 1968). "The Location of the X-ray Source in Vela". The Astrophysical Journal 154 (11): 71-4. http://adsabs.harvard.edu//abs/1968ApJ...154L..71G. Retrieved 2015-12-15.
- ↑ Guido Alpa (1994). "General Principles of Law". Annual Survey of International & Comparative Law 1: 1. http://heinonlinebackup.com/hol-cgi-bin/get_pdf.cgi?handle=hein.journals/ansurintcl1§ion=4. Retrieved 2012-04-29.
- ↑ http://www.ieer.org/fctsheet/uranium.html
- ↑ http://faculty.ncc.edu/LinkClick.aspx?fileticket=Fkhb0%2FAcPfE%3D&tabid=1920
- ↑ Chung Chieh (December 1997). Hydrogen Spectra. Waterloo, Ontario, Canada: University of Waterloo. http://www.science.uwaterloo.ca/~cchieh/cact/c120/hspectra.html. Retrieved 2012-06-06.
- ↑ Eric Hilbert (May 28, 2012). Deep-Sky Wonders. State College, Pennsylvania: Starlight Astronomy Club. http://ehilbert.wso.net/Starlight/deep_sky_wonders.htm. Retrieved 2012-06-06.
- ↑ 154.0 154.1 154.2 T. Sivarani; P. Bonifacio; P. Molaro; R. Cayrel; M. Spite; F. Spite; B. Plez; J. Andersen et al. (January 2004). "First stars IV. CS 29497-030: Evidence for operation of the s-process at very low metallicity". Astronomy and Astrophysics 413 (1): 1073-85. doi:10.1051/0004-6361:20031590. http://arxiv.org/pdf/astro-ph/0310291.pdf. Retrieved 2012-06-02.
- ↑ Jesse D. Bregman; Joel N. Bregman (May 15, 1978). "The violet opacity of carbon stars". The Astrophysical Journal 222 (5): L41-3. doi:10.1086/182688.
- ↑ W. H. Wright (August 1927). "Photographs of Venus made by Infra-red and by Violet Light". Publications of the Astronomical Society of the Pacific 39 (230): 220-1. doi:10.1086/123718.
- ↑ Nathan Smith; Jon A. Morse; Nicholas R. Collins; Theodore R. Gull (August 2004). "The Purple Haze of η Carinae: Binary-induced Variability?". The Astrophysical Journal 610 (2): L105-8. doi:10.1086/423341.
- ↑ 158.0 158.1 Antony Cooke (2005). Visual Astronomy Under Dark Skies: A New Approach to Observing Deep Space. London: Springer-Verlag. pp. 180. ISBN 1852339012. http://books.google.com/books?id=SXmrBfl4H3sC&lr=&source=gbs_navlinks_s. Retrieved 2011-11-06.
- ↑ Fred L. Wilson (December 1968). "Fermi's Theory of Beta Decay". American Journal of Physics 36 (12): 1150-60. http://microboone-docdb.fnal.gov/cgi-bin/RetrieveFile?docid=953;filename=FermiBetaDecay1934.pdf;version=1. Retrieved 2012-06-24.
- ↑ Lawrence M. Krauss, Scott Tremaine (January 1988). "Test of the Weak Equivalence Principle for Neutrinos and Photons". Physical Review Letters 60 (3): 176–7. doi:10.1103/PhysRevLett.60.176. http://link.aps.org/doi/10.1103/PhysRevLett.60.176.
- ↑ Rosaly MC Lopes (2006). "Io: The Volcanic Moon". In Lucy-Ann McFadden. Encyclopedia of the Solar System. Academic Press. pp. 419–431. ISBN 978-0-12-088589-3.
- ↑ Lopes, R. M. C.; et al. (2004). "Lava lakes on Io: Observations of Io’s volcanic activity from Galileo NIMS during the 2001 fly-bys". Icarus 169 (1): 140–174. doi:10.1016/j.icarus.2003.11.013.
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