Two decades ago after the world's first comprehensive nuclear test ban was approved in 1996, the United Nations decided to embark on the ambitious engineering feat of creating a global network of sensors that could detect illegal nuclear tests.

That system is known as the International Monitoring System—the world’s first planetary surveillance network.

Although the Comprehensive Nuclear Test-Ban Treaty has still not been ratified by the United States, and is therefore stalled from taking effect, the surveillance system it has generated is allowing scientists to do things they never envisioned.  

The system has picked up everything from the sounds of the 2011 Japanese earthquake, to the sounds of whales near the Juan Fernandez islands, to the sound of the Chelyabinsk meteor entering the atmosphere, and the sounds of icebergs, oil rigs, and much more. 

Randy Bell is the Director of the International Data Centre Division of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). He explains how the nuclear detection system has yielded unexpected scientific discoveries.

Test yourself—can you name these sounds? Take our quiz below.