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APOD: 2023 February 26 Á Saturns Iapetus: Moon with a Strange Surface
Explanation:
What would make a moon look like a walnut?
A strange ridge that circles
Saturn's moon
Iapetus's equator, visible near the bottom of the
featured image,
makes it appear similar to a popular
edible nut.
The origin of
the ridge remains unknown, though, with hypotheses including ice that welled
up from below, a ring that crashed down from above,
and structure left over from its formation perhaps 100 million years ago.
Also strange is that about half of
Iapetus is so dark that it can
nearly disappear when viewed from Earth, while
the rest is, reflectively, quite bright.
Observations
show that the degree of darkness of the terrain is strangely uniform,
as if a dark coating was somehow recently applied to an ancient and highly cratered
surface.
Last, several large impact basins occur around
Iapetus, with a 400-kilometer
wide crater visible near the image center, surrounded by
deep cliffs that drop sharply to the crater floor.
The featured image was taken by the Saturn-orbiting
Cassini spacecraft during a
flyby of Iapetus at the end of 2004.
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Iapetus
Publications with words: Iapetus
See also: