The Sounds of Saturn

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Wondering what to get that geeky astronomy buff you're dating for Valentine's Day? How about a newly available DVD featuring breathtaking images of Saturn's rings set to an original piece of music? The music in question is the 10-minute-long "Anillos" ("rings" in Spanish), composed by Grammy-nominated Cornell University music professor Roberto Sierra in 2008 for the annual meeting of the American Astronomical Society's Division for Planetary Sciences.

This recording was made in 2008 at Cornell's Bailey Hall by the Cornell Symphony Orchestra. The video images come from NASA's Cassini-Huygens mission currently orbiting Saturn. And 17th century astronomer and musician Christian Huygens provided inspiration to the composer from beyond the grave: Sierra read several of his essays while composing the piece. Check out a sample of the music here. If you like what you're hearing, you can buy the "Anillos" DVD from Buffalo Street Books for $15, just by emailing buffalostreetbooks@hotmail.com.

This isn't the first time a composer has been inspired by Saturn: the sounds of Saturn are inspiring, too. Diehard Alien fans are scratching their heads and pondering, "But I thought in space, no one could hear you scream?" Technically, this is correct: sound needs a medium through which to propagate, and there isn't much of one in deep space, which is about as close to a cold, dark perfect vacuum as you can get. But there's some fine print. Poke around between the planets and other celestial bodies, and you'll find plasma (hot ionized gas), i.e., in the atmospheres of Venus, Mars, and Saturn's moon Titan, not to mention Ganymede, one of the moons of Jupiter. Plasma gas is thinner (by a lot) than the Earth's atmosphere, but it's just dense enough to allow sound waves to propagate.

In fact, the sounds of space are far more varied and complex than on Earth, because of the ionization: plasmas produce a mixture of acoustic and electromagnetic waves (the latter usually in the radio frequency of the spectrum). What do plasma waves sound like? It depends. Lightning produces

whistling sounds, regardless of whether it strikes on Earth or on

Jupiter, and of course, so do the charged particles in the Aurora Borealis. The magnetic fields surrounding the planets can trap

electrons, producing bird-like chirps. And the sun emits high-velocity

plasma known colloquially as the solar wind, which produces turbulent

shock waves and an accompanying roaring boom. The rings of Saturn sound like this:

When Don Gurnett's team first launched a plasma wave receiver into

Earth's orbit in 1962, they were "astonished to find that space is

filled with a rich variety of sounds." Gurnett is a physicist at the

University of Iowa who builds plasma wave receivers for NASA. He's been

collecting recordings

of space sounds ever since (more than 40 years now!), from all the

major missions, including Voyager I, Galileo, and Cassini.

And around 2001, minimalist composer Terry Riley drew from Gurnett's recorded space sounds while composing "Sun Rings" for the Kronos Quartet. "Sun Rings" is a suite of 10 "spacescapes," each a complex layering of musical elements combining celestial sounds with projected space images and the world-famous string quartet in a live multimedia production. He's said in interviews that the crackling and squealing sonic patterns from the magnetic field around Ganymede reminded him of a voice saying "beebopterismo" — and that became the starting point for one of the movements in the "Sun Rings" suite.

"Sun Rings" first debuted in 2002, and has been performed all over the world since then, garnering rave reviews. The Los Angeles Times dubbed it "an empyrean masterpiece" that ushered in "a whole new chapter in the age-old quest for a music of the spheres." You can hear samples in this NPR story.

I don't know if "Anillos" will garner similar rave reviews, but it's nice to see Saturn spreading its rings and getting some musical tributes.