sixteen-seventeen day moon |
Tonight the Mare Crisium will be visible in its entirety for the last time before the terminator sweeps westwards across it. Running northwards from Crisium in a line roughly as long, three craters show strongly in the lunar twilight: smooth class 5 Cleomedes, class 1 Geminus and the old walled plain Messala. Further towards the northern lunar pole, as far again as Messala from Crisium, is the prominent dark oval of class 5 Endymion.
To the south of Crisium by slightly more than its length is class 1 Langrenus. It shows strong relief in this light, very different to its bright ring during the full moon. South of Langrenus by roughly its diameter is the slightly larger class 5 Vendelinus. In contrast to the sharp, youthful outline of its neighbour to the north, its degraded contours reveal its considerable age. To its south, at a similar distance again, lies class 5 Petavius, a ring mountain with its large multiple central peak showing well.