Explanation:
The sprawling Caloris basin
on Mercury
is one of the solar system's largest impact basins.
Created during the early history of the solar system by the impact of
a large asteroid-sized body, the basin spans about 1,500 kilometers
and is seen in yellowish hues in
this enhanced color mosaic.
The image data is from the January 14th
flyby of the
MESSENGER spacecraft,
captured with the
MDIS
instrument.
Orange splotches around the basin's perimeter are now thought to be
volcanic vents,
new evidence
that Mercury's smooth plains are indeed lava flows.
Other discoveries at Mercury
by NASA's MESSENGER mission include
evidence that Mercury, like planet Earth, has a global
magnetic field
generated by a
dynamo
process in its large core,
and that Mercury's surface has
contracted significantly as its core cooled.
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