October 26, 2007	Friday	Shawwal 13, 1428

WASHINGTON: Big chunks of a moon that was smashed long ago perhaps by a comet have been detected in Saturn’s outermost ring, shedding light on the formation of the planet’s grand ring system, scientists said on Wednesday.

A camera on NASA’s Cassini spacecraft spotted wakes ahead of and trailing behind these fragments, where other ring material has been affected by the gravitational forces exerted by the pieces, they said.

The rings encircling Saturn are one of the most dramatic features of the solar system. The other gaseous planets in the solar system — Jupiter, Uranus and Neptune — also are encircled by rings, but they are not as spectacular.

The scientists called the fragments seen in this relatively narrow belt within Saturn’s outermost ring “moonlets.” They were not directly observed by Cassini, but the scientists inferred their existence because of the eight propeller-shaped wakes.It appears some of the fragments are as big as a sports stadium, the scientists said.

“There was probably a bigger moon of at least 20 miles (32 km) in diameter or larger orbiting at that place,” Miodrag Sremcevic of the University of Colorado at Boulder’s Laboratory for Atmospheric and Space Physics, one of the researchers, said in a telephone interview.

“And that moon had the unfortunate fate to be struck by a large meteoroid or comet and was destroyed into pieces. And now what we see today are the remaining shards of that moon,” said Sremcevic.

The findings represent the first evidence of a “moonlet” belt in any of Saturn’s rings, according to Sremcevic.

Saturn’s innermost moon, Pan, is about the same size as the doomed moon, Sremcevic said.

The collision that shattered it took place perhaps 100 million years ago.—Reuters