This weekend the Moon is still young, early in its new phase. While many people look for the first quarter moon to do their lunar observing, this is a great time to study other "less traveled" geographic features of Earth's closest neighbor. There will be many craters, rilles and seas in perfect contrast on this weekend's young Moon - some of them even visible through binoculars. Here are six easy-to-locate features and what you'll need to see them. If you're up for it, get out a pad of paper, some soft pencils, and try drawing a few of these. Drawing at the eyepiece is truly the best way to hone one's observing skills - you will literally see more!
Friday August 9
Mare Crisium is the most prominent sea on the Moon that you will notice tonight, covering an area of 375 miles by 345 miles. It is very circular and has a dark floor, flooded by lava during impacts on the Moon's surface. Notice as well the fine wrinkle-ridges and lots of craterlets. Obvious on the floor is the crater Pickard, 14 miles wide and over a mile deep. A 10x binocular is great for this feature, although you certainly will be able to note this Mare with the unaided eye.
Endymion is a crater containing steep outer slopes and very high inner walls, especially to the southeast. This too is a 10x binocular target, and will certainly make a beautiful sight in a telescope with its walls greatly detailed with razor-sharp shadows.
Cleomedes and Rima Cleomedes are excellent features close to tonight's terminator, or the line of contrast between light and shadow. Cleomedes is a walled plain easy to enjoy with 50mm of aperture. Its slopes have numerous craterlets, and its floor contains Rima Cleomedes and a small mountain. A 10x binocular will show these features. Rima Cleomedes will require a 200mm scope, but this will reveal a 36 mile long Y shaped feature crossing the crater's floor.
Saturday August 10
The crater Atlas and the Y shaped rilles inside it, called Rima Atlas, is a particularly interesting sight. The floor of Atlas is rough, and contains a central mountain and some craterlets. You can see all this with a 50mm telescope. To see Rima Atlas, a 200mm telescope is recommended.
Hercules is the close neighbor of Atlas, forming an outstanding pair. Hercules has very steep slopes, with the crater Hercules D to its southeast. The inner walls have remarkable terraces, and note the stained sinks on its floor, caused by darker lava. A 50mm instrument will get you there.
Cauchy Tau, Cauchy Omega, Rupes Cauchy and Rima Cauchy are all associated with volcanism. Cauchy Omega is a volcanic dome, with a crater on top. To its south is another dome, Cauchy Tau, which is crater-less. Rupes Cauchy is a fault line running south-east to north-west, while Rima Cauchy is a short rille in the form of an 'S.' Plenty to see, even a bit of challenge in this section identifying the numerous features. 100mm for the domes, 200mm for the finer targets.