Explanation:
Why does Mercury have so many rayed craters?
No one is sure.
The robotic
MESSENGER spacecraft that is taking unprecedented images as it swoops past the innermost planet has provided dramatic confirmation that
Mercury has more
rayed craters than
Earth's Moon.
Pictured
above,
a particularly spectacular rayed crater spanning approximately 80 kilometers was imaged by
MESSENGER
during last month's flyby from about 20,000 kilometers up.
The rays prevalence is a mystery because
space weathering
effects such as dust accumulation and
solar wind attenuation should be greater on Mercury than on the Moon.
Hypothesized solutions currently include the
optical properties of Mercurian dust,
and that Mercury's high mass and proximity to the Sun cause more
violent impacts, thus typically raising more light material.
MESSENGER will buzz past Mercury again next year before entering orbit in 2011.
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