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Credit & Copyright: Noel Donnard
Explanation:
Point your telescope
at tonight's first quarter Moon.
Along the terminator,
the shadow line between night and day,
you might find these two large craters
staring back at you with
an owlish gaze.
Alphonsus
(left) and
Arzachel
are ancient impact craters on
the north eastern shores of Mare Nubium, the lunar Sea of Clouds.
The larger Alphonsus is over 100 kilometers in diameter.
A low sun angle highlights the crater's
sharp 1.5 kilometer high central
peak in bright sunlight and dark shadow.
Scouting for potential Apollo moon landing sites, the
Ranger 9 spacecraft
returned closeup photographs of Alphonsus before
it crashed in the crater just northeast (left) of its central mountain in 1965.
Alpetragius,
between Alphonsus and Arzachel,
is the small crater with the deeply shadowed floor and
overly large central peak.
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A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Moon
Publications with words: Moon
See also: