Ring Around the Planet

It's like a glittering ring of fairy dust, with a diameter of 24 million kilometers.

That's big. In fact, it's 200 times the diameter of Saturn, the planet it encircles. It's also the biggest planetary ring ever found. According to an article in Science News, "A billion Earths could fit inside the ring. "

Don't bother taking out your telescope to see the ring, which extends out beyond Saturn's farthest moon, Phoebe. It's so gossamer-thin that it took NASA's infrared Spitzer Space Telescope to find the ring in February.

Researchers estimate that the ring has a mass of about a trillion kilograms -- which means it's exactly the right size to account for a kilometer-wide chunk that's missing from the surface of Phoebe.

In addition to explaining the missing bits of Phoebe, the ring may also settle an old debate about why another Saturnian moon, Iapetus, appears to be much darker on one side than on another. According to the article, "Throughout the solar system's history, material from the ring could have generated a coating on Iapetus 20 centimeters thick." Said researcher Joseph Burns, "The Phoebe ring is the smoking gun that identifies the culprit in coating Iapetus."

Whatever its impact on the moons of Saturn, there's no doubt that the discovery of a new Saturnian ring is mesmerizing the inhabitants of the third rock from the sun. The reason? It's just... so pretty!

Image courtesy of NASA/JPL-Caltech/Kec