The Chorus of the Radiation Belts
Far above the Earth, two NASA spacecraft recorded radio waves that, turned into sound, chirp and whistle like birds at dawn.
What was reported
The Van Allen belts are two rings of charged particles trapped by Earth's magnetic field, thousands of kilometres up. In 2012 NASA sent two probes to fly through them and study the radiation there.
Their instruments recorded waves called 'chorus': bursts of radio waves at frequencies people can hear, once converted to sound. They come as rising chirps and whistles, rushing together like a dawn chorus of birds. Radio listeners on the ground had heard them faintly for decades.
Explanations offered
Chorus waves are made by electrons spiralling in the magnetic field, and they can speed some electrons up to nearly the speed of light, creating 'killer electrons' that can damage satellites. The probes helped explain how the belts swell and shrink.
- When
- Recorded 2012–2019
- Where
- In orbit, in the Van Allen radiation belts
- Witnesses
- NASA's Van Allen Probes
- Status
- Explained
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