Twenty-Four Day Old Moon‡

The broad crescent Moon rises in the very early hours after midnight and will be visible until early afternoon. It will transit after sunrise, so the best time to observe will be during the last hours of darkness, close to dawn.


Key Features to Observe Tonight

The great Mare Imbrium basin lies half in lunar darkness tonight. On the northwestern end of Mare Imbrium, the smooth floored Sinus Iridium shows nicely, its own northwestern shore contained by the crescent Jura Mountains. The crater Bianchini which impacted near the center of this mountain arc, appears somewhat like a jewel in a ring.

The westward-advancing terminator has now about reached Copernicus, which will show high relief tonight. To the southwest of Copernicus at about two diameters, on Oceanus Procellarum, lies the crater Reinhold, which makes a nice display tonight. Moving further away from Copernicus on nearly on a straight line at about twice the distance, is the crater Lansberg. Lansberg is slightly smaller than Reinhold and appears tonight as a dark circle with a bright rim with a double central peak.

Due south, the Riphaeus Mountains around Mare Cognitum appear quite bright tonight. Immediately to their west is a bright halo of ejecta material surrounding the crater Euclides. A very small crater, with tonight's illumination the dark circle of the crater itself is visible.

Southeast from Euclides, at Mare Nubium's western shore, lies the fine ring plain Bullialdus, which is soon to be engulfed by the terminator. Contrasts are sharp on it and its smaller two sister craters tonight. Mare Nubium itself lies half on the dark side tonight.

Traveling further southwest is the crater König, which makes good viewing tonight. About the same distance away from Bullialdus again is are twin dark floored craters, Campanus, to the northwest, and Mercator on the southeast. The similarity they displayed two weeks earlier has disappeared under tonight's low light which magnifies small differences.

We end with a mention of the crater Hainzel, a complex feature of three intermingled craters. Tomorrow will mark the last opportunity to observe this fascinating triplet during this lunation.


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