Telescope captures new rings, moons on Uranus

SAN JOSE, Calif. — A new discovery by Mountain View, Calif., scientists is improving the image of the distant blue-green planet Uranus.

NASA's Hubble Space Telescope has captured photographs of two new rings and two new moons around the seventh planet from the sun, the researchers reported in Friday's issue of the online version of the journal Science.

What is most exciting is not the discovery of the newfound ring-moon system but data that reveal its erratic and evolving behavior, showing that not all is serene in our solar system, the team said at a news conference.

"It is more evidence that our solar system is a dynamic place, somewhere very active," said Mark Showalter of the Center for Search for Extraterrestrial Intelligence Research, who teamed with Jack Lissauer of NASA-Ames Research Center on the project.

"By watching the processes, while they are occurring" on Uranus, "we can better understand the growth rate of planets."

Over the years, Uranus has gained a reputation as one of the less interesting planets in the solar system. That is because astronomers' last good look in 1986, from Voyager 2, was during its 21-year winter, when it resembled a bland ball.

New higher-resolution photographs shot in 2003 from the Hubble telescope, recently upgraded with better equipment, tell a different and more detailed story.

The moons and rings create a chaotic and densely packed place, with lots of gravitational jiggling, altered orbits and spinning dust, the photographs show.

The new moons, named Cupid and Mab, bring the number of moons circling Uranus to 27, the most of any planet. Uranus now has a total of 13 rings.

Because it is such a compact system, there are many collisions and much dust and debris. Some of this litter becomes rings, perhaps going on to create new moons, the researchers said.

"Moons appear and disappear; rings appear and disappear," Lissauer said.

The discovery has little effect on our understanding of Earth, the scientists said. However, what is easy to see in Uranus, in a brief period, is likely to be happening elsewhere in the solar system, the scientists agreed.