Astronomy Picture of the Day
    


The Lunar X
<< Yesterday 10.12.2016 Tomorrow >>
The Lunar X
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.

January
February
March
April
May
June
July
August
September
October
November
December
 < December 2016  >
Mo Tu We Th Fr Sa Su



1234
567891011
12131415161718
19202122232425
262728293031
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
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:
All publications on this topic >>