In space, no one can hear you scream. So how did two NASA probes record Earth singing?
Suspended in the dark cosmos, Earth sings to itself in a high-pitched chorus of chirps and beeps. This song is a product of very low frequency radio waves generated by lightning strikes or excited electrons zipping through the Van Allen Belts, two vast swaths of radiation surrounding Earth. While ham radio operators have long detected this eerie planetary sound using inexpensive receivers, the recent recording by specially designed antennas on NASA's twin Van Allen Probes is one of the clearest examples ever captured. But could Earth's chorus be a siren song? The probes are now on a quest to find out whether these radio waves might be powering up otherwise harmless electrons in the Van Allen Belts, turning them into "killer electrons" capable of damaging satellites and astronauts. Watch the videos to hear and learn more about this rare recording.