Explanation:
Stark shadows of
mountains and
crater walls stand out along
the lunar terminator, or shadow line between night and day,
in this
telescopic image.
Of course, if viewed from the
lunar surface near the terminator line,
the Sun would be rising and still close to the lunar horizon.
But the picture's inset at the left highlights a more elusive
lunar sunrise phenomenon.
Streaming through a gap in the eastern wall of 45 kilometer wide
Hesiodus crater,
the low-angle sunlight produces
a long sunrise ray
playing along the otherwise shadowed crater floor.
Sunrise rays are short-lived and can be rewarding to spot for
Moon
enthusiasts with telescopes.
Seen in Hesiodus and other craters, the ray timing can be
calculated based on the
observer's
location.
This picture of a first quarter Moon was
recorded at 23:45 UT on February 22nd from Stuttgart, Germany.
In the inset, the larger crater Pitatus is at the right.
For location, Hesiodus and Pitatus are circled at the bottom of the picture.
