Ancient Craters of Southern Rhea
Explanation:
Saturn's ragged moon Rhea has one of the oldest surfaces known.
Estimated as changing little in the past billion years,
Rhea shows
craters
so old they no longer appear round their
edges have become compromised by more recent cratering.
Like
Earth's Moon,
Rhea's rotation is locked on Saturn, and the
above image shows part of
Rhea's surface that always faces Saturn.
Rhea's leading surface is more highly cratered than its trailing surface.
Rhea is composed mostly of water-ice but is thought to include about 25 percent
rock and metal.
The
above image
was taken by the
robot Cassini spacecraft now orbiting Saturn.
Cassini swooped past
Rhea
last month
and captured the
above image
from about 350,000 kilometers away.
Rhea
spans 1,500 kilometers making it Saturn's second largest moon after
Titan.
Several
surface features on Rhea
remain unexplained including
large light patches like
those seen near the image top.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
