Yesterday, a series of narrow radio beams from Jupiter reached Earth ... but they weren't from NASA's Juno spacecraft. They came from Jupiter itself. Natural radio lasers in Jupiter's magnetosphere send shortwave signals into space and occasionally they sweep past Earth.
"I picked them up in broad daylight,"
says Thomas Ashcraft, who operates an amateur radio telescope in rural
New Mexico. Click on the image to hear the static-y sounds that emerged from his loudspeaker.
Each pop and click is the sound of a single beam washing over our planet. "The interesting thing to me," says Ashcraft, "is that unbeknownst to us Jupiter radio beams are often sweeping over us, actually washing over our bodies if we are outside at the time."
The lasers are powered, in part, by electrical currents flowing between Jupiter's upper atmosphere and the volcanic moon Io. When the geometry is just right, and Earth is in line with the beams, they are easily detected by ham radio antennas on Earth. Jovian "S-bursts" (short bursts) and "L-bursts" (long bursts) mimic the sounds of woodpeckers, whales, and waves crashing on the beach. Here are a few audio samples:
S-bursts, S-bursts (slowed down 128:1),
L-Bursts
Now is a good time to listen to Jupiter's radio storms. The giant planet is high in the sky at sunset and, thanks to the crashing solar cycle, background noise is low. There are few solar radio bursts to overwhelm Jupiter and terrestrial stations are having a hard time bouncing over the horizon as ionizing radiation from the sun ebbs. Ready to start taking data?
NASA's Radio Jove Project explains how to build your own receiver.
