Saturn's third largest moon Iapetus is a satellite
with two faces. One half sports white-as-snow shine while the other
remains black as coal.
The moon's duality has long perplexed astronomers,
but with the Cassini-Huygens spacecraft currently
orbiting Saturn, scientists are now catching
their best views of the odd-looking Iapetus.
This series of images taken
by Cassini are the clearest ever taken of Iapetus, showing its anti-Saturn side
that faces away from its parent planet. Many impact craters are visible in the
bright region, and for the first time researchers can make out craters in the
dark terrain as well.
A line of mountains, appearing as a string of bright dots, can be seen in the
left and center images, as well as along the eastern limb of the rightmost view.
Originally detected by NASA's Voyager spacecraft in the 1980s, these peaks
may give the tallest mountains on Earth, Io and Mars a run for their money
though further observations are needed to pin down their elevations.
Also visible is a large circular feature in the
southern hemisphere, most likely the result of an impact, spanning a diameter of
250 miles (400 kilometers). Cassini first detected the object
in low-resolution observations two months ago.
The spacecraft caught these three views between Oct.
15-20, 2004 with its narrow angle camera, combining images taken with
ultraviolet, green and infrared filters to assemble the two color pictures at
left and center. The right image was taken with visible light
and the bottom three images are identical to
their upper row counterparts, with the addition of a coordinate grid.
The Cassini-Huygens mission is a joint effort by
NASA, the European Space Agency and the Italian Space Agency.
-- SPACE.com Staff
Credit: NASA/JPL/Space Science
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