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Credit & Copyright: Alessandro Marchini
(Astronomical Observatory,
DSFTA - Univ. of Siena),
Liceo "Alessandro Volta" Student Astronomers
Explanation:
The striking X appearing in this
lunarscape is easily
visible in binoculars or a small telescope.
Yet, not too many have seen it.
The catch is this lunar X is fleeting, only apparent
in the hours before the Moon's
first quarter phase.
At the terminator, or shadow line between lunar day and night,
the X illusion is produced by a configuration of the craters
Blanchinus, La Caille and Purbach.
Near the Moon's first quarter phase, an
astronaut standing close to
the craters' position would see the slowly rising Sun very
near the horizon.
Temporarily, the crater walls would be in sunlight
while the crater floors were still in darkness.
Seen from planet Earth,
contrasting sections of bright walls against
the dark floors by chance look remarkably like an X.
This sharp image of the Lunar X was captured at approximately 16:45 UT
on December 6, 2016.
For extra
credit, sweep your gaze along the lunar terminator and
you can also spot the Lunar V.
Liceo "Alessandro Volta" Student Astronomers
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Based on Astronomy Picture
Of the Day
Publications with keywords: Moon
Publications with words: Moon
See also: