Saturn’s Moon Iapetus Has Some Unusual Qualities

December 11th, 2009

Saturn has so many moons you wonder how they can even keep track. It is no surprise that some of them may even be quite unusual as is the case with Iapetus.

Saturn has 61 moons (confirmed orbits), but only 53 are named, and most relatively small. There are also hundreds of known moonlets embedded within Saturn’s rings.

Iapetus is so odd because it looks like it has hemispheres with completely different colors on each side. One side is completely black, while the other is white as the driven snow living together in perfect harmony (la la la). Take a look:

lapetus saturn moon

Recent images taken of the moon may have revealed a bit more information on the rare phenomenon. Scientists that spend all day in observation in need of the best acne treatment share some results of a new discovery.

Cassini-Huygens spacecraft, has been orbiting Saturn since 2004. New images offer the most compelling evidence to date of why and how the moon got its yin-yang appearance, as well as clues to how other such satellites might have formed in the early universe. Analyzed by a research team that includes Cornell scientists, the images are detailed in the Dec. 10 online edition of the journal Science.

“This is not the most fundamental problem in the world,” said research team member Joseph A. Burns, Cornell’s Irving Porter Church Professor of Engineering and professor of astronomy. “But it’s an enigma that’s been puzzling astronomers for centuries.”

Using pictures taken by Cassini, particularly during a September 2007 close fly-by, the scientists assert that Iapetus’ darker half, called Cassini Regio, is the result of the planet’s leading side getting bombarded by dusty debris from another Saturnian moon, Phoebe, which orbits in the opposite direction beyond Iapetus.

It is a longstanding theory, but in a paper published in the journal Nature in October, three Cornell-trained astronomers announced the discovery of an enormous ring of debris ¬- 10,000 times the area of Saturn’s famous main ring system — around Saturn, near Phoebe’s location, pointing to it as the ring’s source. Burns calls this ring the “smoking gun” supporting dust hitting Iapetus and other moons around Saturn.

“The ring of collisional debris that has come off Phoebe and its companion moons is out there, and now we understand the process whereby the stuff is coming in,” Burns said. “When you see the coating pattern on Iapetus, you know you’ve got the right mechanism for producing it.”