The Man in the Moon

Image taken from our Backyard 08-03-2017 with a 90mm ETX Mak-Cassegrain telescope. Libration providing good views of Mares: Marginis and Smythii on the Lunar limb. The added image from NASA shows the planet Earth rising over the rim of Mare Smythii. The image was taken from the command module of Apollo 11 looking towards Mare Fecunditatis as Apollo 11 re-emerge from the farside.

Libration of the Moon: an apparent or real oscillation of the moon, by which parts near the edge of the disc that are often not visible from the earth sometimes come into view. The moon is tidally locked to Earth and that is why we can only view the nearside, the far side is forever out of sight. From Earth we can see slighltly more than one hemisphere, in fact we can see 59% of the moon's surface and this is due to libration.

In detail, there are three types of lunar libration:

• Libration in longitude results from the eccentricity of the Moon's orbit around Earth; the Moon's rotation sometimes leads and sometimes lags its orbital position.
• Libration in latitude results from a slight inclination (about 5 degrees) between the Moon's axis of rotation and the normal to the plane of its orbit around Earth. Its origin is analogous to how the seasons arise from Earth's revolution about the Sun.
• Diurnal libration is a small daily oscillation due to the Earth's rotation, which carries an observer first to one side and then to the other side of the straight line joining Earth's and the Moon's centers, allowing the observer to look first around one side of the Moon and then around the other—because the observer is on the surface of the Earth, not at its center. 

 Credit Wikipedia

By Tomruen (Lunar_libration_with_phase_Oct_2007.gif) [Public domain], via Wikimedia Commons

A composite of two images taken from my Backyard. The colour has been enhanced to show changes in surface minerology. I tend to think this is the view I might have out of the window of my imaginary space capsule some 100 miles above the lunar surface as I orbit the moon.

"From a distance, the moon appears to be perfect.  A smooth perfect sphere moving like clockwork around a circular orbit. Up close it is a cratered mass of lava flows and jagged rock that advances, recedes and wobbles along its celestial course - how very much like our species".  Kurt Thrust - Director of the Jodrell Plank Observatory.