twenty-five
day moon
The best time to observe the Moon is during the last hours of darkness, when it will appear as a crescent in the eastern sky.

Kepler With Copernicus absent, the focal point of tonight's Moon is the striking class 1 Kepler, level with the mid-point of the terminator. Its ray system, although now fading, can be traced across much of the Oceanus Procellarum around it. Its rival, just over one Humorum length to the north-north-west, is Aristarchus - less centrally placed, but actually the most reflective area on the face of the Moon, with an albedo of 0.18.

Halfway between Aristarchus and the northern cusp, the Sinus Iridium is bisected by the terminator, and resembles a large semicircular bite taken from the Moon's edge. To its north, across the Jura Mountains which form its rim and on the opposite shore of the last remaining fragment of the Mare Frigoris lies the crater John Herschel, ancient but well defined in this light.

Lunokhod 1 To the south-west of the western end of the Juras, on the plains of Procellarum, the probe Luna 17 softlanded in 1970. Its payload included the rover Lunokhod 1, the first vehicle to travel on lunar soil.

To the south-west of Kepler, just beyond the shore of Procellarum, class 5 Grimaldi remains a dark and distinctive oval. To the south of Kepler and the south-east of Grimaldi, the class 5 walled plain Gassendi occupies the third corner of an equilateral triangle, each with a very different appearance.

Mare Humorum Gassendi is set into the northern rim of the Mare Humorum, which is seen in full for the last time tonight.

To the south-south-east of Humorum by twice its width is Schiller, the most extreme example of an elongated crater, with its longest diameter nearly 21/2 times as great as its shortest.