After last week's announcement that scientists had detected gravitational waves first predicted by Albert Einstein a century ago, everybody is listening to the"chirp" of two black holes colliding. But listening to space is nothing new for radio astronomers.
It turns out, many celestial objects and events produce radio waves. Black holes are actually some of the "most radio-bright objects in the sky," says Michelle Thaller, a research astronomer and deputy director for science communication at NASA's Goddard Space Flight Center. But NASA space probes have recorded radio waves from sources as varied as Earth's magnetic field; lightning on Jupiter; the atmosphere of Saturn's moon, Enceladus; and dust in interstellar space.
"Basically, anything with any energy at all will produce some radio waves," explains Thaller. "Even very low-energy stuff, like cold gas between the stars, that will emit some radio waves. And that's one of the ways we can see things that are very dark and cold."
Wait, see? Or hear? Thaller is quick to point out that radio waves are actually a form of light, not sound. (And, thank goodness for that, or we'd all be bombarded with the full array of radio programming the world has to offer, all the time.) What our radios do is use magnets to transform radio waves into sound waves. And that's what NASA has done - and made public - with a new collection of space "sounds."
Astronomers can use radio waves to not only see objects, but also decipher their composition, or detect changes or events. The less trained ear can simply enjoy the whistles, squeals, pops, and hisses. Thaller says it's a great way for people to connect with parts of space we'll never visit in person.
Earth's (rainforest-like) Chorus, spooky Saturn ... what's your favorite?