Eleven Day Old Moon‡

The Waxing Gibbous Moon will be visible during the late afternoon, setting several hours after midnight. It transits a few hours before midnight, which makes observing ideal tonight, as you view through the least atmosphere in dark skies without requiring a late night of observing.


Key Features to Observe Tonight

The westward movement of the terminator continues, tonight revealing several exciting new sights. The huge smooth Oceanus Procellarum, extending to the lunar limb and beyond, continues to be exposed, and begins to show its shape tonight. To its north, the long, narrow Mare Frigoris is now seen in its entirety.

Within Oceanus Procellarum, close to the terminator, is Aristarchus. At full Moon this is the brightest object on the lunar surface. Southeast of it is Kepler, a beautiful crater with a prominent ray system which first appeared last night. It will continue to improve in appearance over the coming nights. Copernicus, nearly due east from Kepler, forms the third corner of this triangle of ray craters. Their bright rays appear to connect them, forming an unusual sight over the next few evenings.

Far south of Kepler, south of the equator, about midway to the pole, is the large crater Gassendi, a bright ring with a particularly convoluted floor. Gassendi shows an extensive network of rilles on its crater floor. Digital cameras now make it possible to obtain very high magnification images with smaller aperture telescopes, and Gassendi is a good target for such work. With good transparency much detail can be seen. Gassendi has been impacted by Gassendi A on its north rim.

Gassendi's south wall has almost disappeared from lava flooding by Mare Humorum, to its south. Mare Humorum, the Sea of Moisture is one of the smaller but better defined seas. It is a fine sight with small craterlets and ridges on its surface worth exploring.

Half again as far south, close to the terminator, one of this author's favorite craters is revealed tonight: Schiller. Although somewhat foreshortened by its proximity to the limb, its elongated shape is real and pronounced, being over two and a half times. Watch its appearance change over the next few nights as the shadows shift.

Northeast of it, Tycho is now very bright. A very interesting dark halo between the crater and its ray system begins to become apparent now. Longomontanus is the large crater lying midway between them.

Close to the terminator south of Schiller is a trio of craters that show nicely tonight and are easy to identify. The northernmost is Zucchius, then come fractionally larger Bettinus and Kircher. They all appear quite foreshortened.


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