twenty-eight
day moon
If you succeed in observing the Moon tonight, it will be a significant achievement. It is now very close to the Sun, and is an extremely slender crescent against a bright background, close to the horizon and therefore seen through a considerable thickness of atmosphere. These conditions apply to the one day Moon too, but now are compounded by the probable mistiness of the colder morning, and the need to locate this difficult object without the guidance of the Sun's setting position. The least difficult time will be around the autumnal equinox in the northern hemisphere, or the vernal equinox in the southern hemisphere, when the Moon will be at it greatest angle above the horizon. It will rise in the east very shortly before sunrise tomorrow morning, and is unlikely to clear the horizon by more than ten degrees before the Sun emerges.

It is difficult to be certain which features will be visible tonight. If there is due to be an eclipse at the time of the coming new moon, the Sun's light will be falling directly on the western side of the Moon, but otherwise the crescent may be centred significantly towards the north or south or the lunar disc. Also, the effects of libration will affect a high proportion of the features on the Moon's thin crescent.

Near the midpoint, a pair of adjacent craters appear as a foreshortened figure of eight. The southern component is the large class 3 Riccioli, with its distinctive, partly light and partly dark floor, whilst the slightly smaller northern one is the ancient Hedin.

To the north of this pair, at a separation roughly the same as their combined length, is the considerably smaller class 2 Cardanus. Just to its north stands another identically-sized crater, Krafft, which although extremely old and eroded actually shows slightly better than its southerly neighbour.