Two Day Old Moon‡

The Moon is moving further away from the Sun, so it sets later each night. The Moon is still low near the horizon, but in darker skies with the better contrast a dark sky creates. The Moon's thin crescent will be visible for a few hours after sunset, low in the west.

The prominent craters on tonight's tour all lie on the terminator, which splits them midway, half being in light, half in darkness.


Key Features to Observe Tonight

North of the midpoint of the terminator, the eastern half of Mare Crisium is now visible. It appears very smooth at this time, and the surrounding highlands are not yet prominent. The contrast between its darkness and the brightness of the surrounding highlands will become more obvious in a few more nights.

To the north of Mare Crisium by one diameter is the walled plain Messala, aged looking, with many subsequent impacts.

Directly south of Crisium about the same distance away is the crater Langrenus. Named after John Langrenus, it is the only survivor from his system of names on the very first lunar map in 1645.

To the south of Langrenus by about its diameter is the larger walled plain Vendelinus. Its outline interrupted by smaller and more recent craters.

Further south, by a slightly bigger separation, is the crater Petavius, with its massive central peaks rising high above its floor.


‡with permission from Lunar Discoverer User's Manual by Robert Duvall, 2013