[meteorite-list] Scientists Discover Two More Rings Around Uranus

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Dec 22 13:38:01 2005
Message-ID: <200512221755.jBMHtKE01457_at_zagami.jpl.nasa.gov>

http://www.orlandosentinel.com/news/custom/space/orl-bk-uranus122205,0,641715.story

Scientists discover two more rings around Uranus
Associated Press
December 22, 2005

LOS ANGELES -- Astronomers announced today they have spied two more
rings encircling Uranus, the first such discovery since the Voyager 2
spacecraft flew past the planet nearly two decades ago.

The faint, dusty rings orbit outside of Uranus' previously known ring
system, but within the orbits of its large moons, said Mark Showalter,
an astronomer at the SETI Institute in Mountain View, California, who
made the discovery.

Details will appear online Friday in the journal Science.

In 1986, Voyager 2 became the first spacecraft to zip past Uranus and
beam back thousands of images of its dazzling rings and numerous moons.
Uranus, the seventh planet from the sun, possesses 11 known rings. Nine
thin rings were previously discovered on Earth, and Voyager 2 found the
10th and 11th arcs.

Scientists peering through the Hubble Space Telescope made the latest
ring discoveries in 2004. Then they went back to process hundreds of
images taken by Voyager and found the rings in the pictures. Scientists
speculate that the rings may not have been discovered during the
spacecraft flyby because of their faintness.

The newly discovered rings are made up of short-lived, faint bands of
dust grains that are constantly being replenished by erosion of larger
space bodies. Scientist think the dust in the outermost ring is being
supplied by the moon Mab, discovered in 2003.

Scientist also measured changes in the orbits of Uranus' inner moons
since 1994. The new measurements suggest the moons are in a "random and
chaotic" fashion, said Jack Lissauer of the NASA Ames Research Center.

Because of the moons' instability, scientists think the satellites will
collide with one another in the next couple of million years.

Uranus, four times the size of Earth, is one of the solar system's
giant, gaseous planets that also include Jupiter, Saturn and Neptune.
Received on Thu 22 Dec 2005 12:55:19 PM PST