six day moon

The whole of the Mare Tranquillitatis, just north of the midpoint of the terminator, and almost all of the Mare Serenitatis which joins it to the north, are now visible. The lonely class 1 crater which shows brightly against the darkness at their junction is Plinius (Pliny). To its west, on the southern edge of Serenitatis, is class 1 Menelaus. Although only 20 miles across, it is clear and well defined, but as the Moon approaches fullness it will become one of its brighter points.

On the north-western edge of Serenitatis, the eastern end of the 17000 foot high Caucasus Mountains is revealed. Following north from here are the conspicuous class 1 Eudoxus, and slightly further to the north the slightly larger ring mountain Aristoteles (Aristotle), also class 1. The smooth area immediately north of here is the eastern end of the Mare Frigoris - a long, narrow plain which will take some six nights to emerge from the nightside.

In the south-west of Tranquillitatis lies the most famous of the many human artefacts left on the Moon: the base section of the Apollo 11 landing module, Eagle, from which Neil Armstrong made the "small step" in 1969. The historic event is marked by the naming of three small, neighbouring craters Armstrong, Aldrin and Collins after the astronauts. By convention, lunar features are named posthumously. These are the only nearside features which break that convention and honour living namesakes.

Level with the centre of Tranquillitatis, in the uplands to its west, the line of the Rima Ariadaeus runs west-north-west. Most rilles, shallow clefts in the Moon's surface, are seen in the smooth mare regions. Ariadaeus is wide enough to show well even against the rough backdrop of the uplands.

Just off the south-western edge of the Mare Tranquillitatis lies class 2 Delambre, very conspicuous for its modest size. South-east from here by about the length of the Mare Crisium is class 1 Theophilus which, together with its similarly sized but progressively older south-westerly neighbours, class 3 Cyrillus and class 4 Catharina, first became visible last night. Some two Crisium lengths south-west of Catharina (ie following a line from Theophilus) lies class 2 Maurolycus, prominent even in the confused landscape of the Moon's southern hemisphere.