spacetoday.net: Giant ring discovered around Saturn

Posted: Wed, Oct 7, 2009, 2:08 PM ET (1808 GMT)
Spitzer image of giant ring around Saturn (NASA/JPL)

NASA's Spitzer Space Telescope has discovered a giant ring around the planet Saturn, bigger than any other planetary ring in our solar system. Astronomers announced Tuesday the discovery of the ring, which extends between 6 and 12 million kilometers from the planet. The tenuous ring is made of ice and dust particles, likely from the moon Phoebe, which orbits Saturn from within the ring. The ring is difficult to detect at visible light wavelengths, which is why it was not detected until observations by Spitzer, an infrared observatory. The ring may explain why another of Saturn's moon, Iapetus, has one bright hemisphere and one dark one; the moon collides with the ring materials to create the dark region of its surface.