I always look forward to the appearance of the 104km diameter crater Plato and surrounding environs as they emerge from the lunar night. There is so much to see there I find imaging irresistible. Usually I don't like to do this wide a field but there's much to enjoy. Plato's terraced walls exhibit ancient slumping and breaches by rimae. South of Plato are the sparkling Montes Teneriffe with 2400m high Mons Pico the large peak on the east (right) end. To the east of Plato is the great gash Valles Alpes with it's central rille seen here (with a 6" telescope) with another isolated mountain peak south of the entrance to the Vallis, Mons Piton (2250m) standing isolated on the plain of Mare Imbrium. In the lower right corner of this image is Cassini (60km) with it's tight ejecta blanket surrounding and interior wrinkles and satellite craters.
Above Plato is a large flat region that is Mare Frigoris, the longest mare in terms of longitude stretching from Sinus Roris and Harpalus north of Oceanus Procellarum some 1500 km almost to Endymion. Notice the three craters on the northern shore of the Mare. They are, left to right or in order of size, Timaeus (34km), Archytas (32km), Protagoras (22km). North of Timaeus is a large very square crater, W Bond (listed as 163 km "diameter"). It has a small rima on the north side. On the west side of W Bond is the crater Epigenes (56km). Lastly the crater north of W Bond is the flat floored crater Barrow (95km). Shadow play on the floor of this crater during the lunar day rewards careful watching.
North of Theophilus, in the lower left corner of this image, is Sinus Asperitatis running diagonally across this image, with the pear-shaped crater Torricelli in the middle. The crater is listed as 24km diameter which refers to the larger portion with extension adding a few more kilometers to the west. This odd shape is due to the merge of two impacts though the wall between the two is very low step. It sits on the northern edge of an unnamed ancient flooded crater some 90km across whose walls can be made out in this low angle sunset lighting. Near the bottom middle of this image is the shadow filled crater Isidorus (43km) that appears pear-shaped as well. Note how the mountains around Isidorus are soft looking, overlain by ejecta from the tremendous Theophilus impact. Compare them to the peaks north of Torricelli. You will see at the top edge of the image the crater Maskalyne (26km) and left *(west) of it is the small crater Moltke (7km) with Rimae Hypatia just south of it. It was just beyond this point, on the north edge of this image where Tranquility Base of Apollo 11 was established. Above Isidorus is yet another pear-shaped crater that points back at Isidorus. This is Isidorus B (30km) and to the left (west) of it is a very curious trench-like feature labeled Isidorus C. It's about 5km wide and 15km long and in LROC Quick Map images looks like a large footprint! It is the result of multiple impacts and later modification from slumping and possibly some volcanic activity. It makes a good study on the best nights with an aperature of 150mm or more.
When the Moon is not quite 10 days old you can get a good look at a few of the more obvious domes in the Mare Nubium area south of Bullialdus. The first key is to locate Kies, the 46km diameter crater at the top of this image with the little tail pointing down. Notice the mild swelling just to the left of the crater. This is Dome Kies Pi or K1. It's 10km in diameter with a little 2km craterlet at the summit, just barely visible here. Going further to the left there are two small clusters of mountains. Just above the farther one is another mild swelling, K3. A third dome is just off the end of the tail of Kies but I never have gotten a good image of it. It may be just to low a feature. Below Kies you see a graben-like rima, Rima Hesiodus that runs some 309 km from Hesiodus just south of it's eastern (right) terminus, the crater with a small central crater (and the nice double walled crater, Hesiodus A just below it) all the way across Palus Epidemiarum north of another crater, Capuanus (61km). On the floor of this crater you can see 3 domes, C1, C2 and C3 as you may have guessed. There are other low swellings around this image near the terminator in this image but I have no guide for any identification beyond these.
In the upper right of this image, adjacent to Hesiodus is the large crater Pitatus (or "Potatoes" as we used to joke). Across from this, on the right side are the twin craters Campanus above and Mercator below both 49km dia. Then in the lower left is the crater Wilhelm (111km). It is a very busy area with lots to see, like that strange straight mountain range in the middle of the image with the small plain below it. You can easily spend a whole evening here!
Seven days into this particular lunation, we had a favorable libration just at the northern edge of the limb on this image. It allowed for a very good view of a couple craters not usually seen so well. The large dark area in the lower left is the north shore of Mare Crisium and Mare Angius the dark meandering patch on the right side of Crisium. Notice just above it is the large crater Cleomedes (129km dia.) and above that is the well defined Geminus (88km). Then at the top edge of the image is Messala (128km) with its nicely terraced walls. Moving towards the limb you see another fairly well defined crater, Berosus (77km) and to the lower right another similar sized crater with a curious dark stripe across it's floor, Hahn (87km). It appears from Lunar Orbiter images and the Gazetteer of Planetary Nomenclature: 1:1 Million-Scale Maps of the Moon, that most of the northeast half of the floor on this crater is simply a darker material than the southwestern half.
On the limb, straight across right from Crisium is a dark floored crater. This is Hubble (83km) not often seen this well with its longitude of 87°. This crater is named after Edwin P. Hubble as is the famous telescope and minor planet (2069) Hubble. Below it is another dark floored crater, Cannon (60km). Further in towards Crisium is the outline of the crater Plutarch (70km) which is usually the near limb feature for this region!
South and east of Posidonius is the crater Romer (41km dia.) seen here at the top of this image with starkly terraced walls and an off center peak on its floor. It's a young crater and its shape is strongly affected by the topography it was created in. Twin 12km craters below it are Brewster on the left and a little lower on the right is Franck. These both sit in the western reaches of Sinus Amoris with Mons Miraldi, a round mound on the southern shore of the Sinus just north of the low walled crater Miraldi (41km). Moving further south is the crater Gardner (19km) and to its west (left) is the flat floored Vitruvius (31km) half in shadow. South and west of Vitruvius is a smaller crater, Dawes (19km) with an interesting set of ridges on the east side of the crater, followed by Plinius (44km) with Rimae Plinius north and Promontorium Archerusiz next to it.
Notice north and west of Vitruvius there are four similar mountain peaks in a row all catching the early morning sunlight. They mark the location of the Apollo 17 landing site marked here with a "O". It is one of the easiest Apollo landing sites to find and once you learn it, Taurus-Littrow will always stand out. The "O" sits in Taurus-Littrow Valley with South Massif being the sunlit mountain to the south and the dimmer light just north of the "O" is North Massif. The little dot to the lower right of the "O" is Bear Mountain named by Harrison Schmidt after a mountain near his hometown in Silver City, New Mexico. Details can be seen in images taken from overhead at the URL: www.lpi.usra.edu/lunar/missions/apollo/apollo_17/landing_site/. All the EVAs and the 37km of driving around in the "Moon Buggy" was done inside that circle and included the most time of any crew on the lunar surface collecting 110.4 Kg of surface samples.
North of the landing site is the flat floored teardrop shaped crater Littrow (19km) and to the left is a field of rimae called Catena Littrow with the small crater Clerke (7km) between them. The rimae are graben-like and therefore fairly wide, about 2km on average. Going further north, following the wrinkle ridge or dorsa that leads out of the Catena we come nearly full circle with the embayment Le Monnier (63km) a very distinctive feature.
Early in every lunation you can see this region on the moon and though I have covered it before, I discovered some remarkable new things on this particular visit. First a little orientation. Notice the Mickey Mouse configuration in the upper left. The left ear is the crater Licetus (77km diameter) and the right is Cuvier (also 77km). Between them is the unusual north-south elongated feature, Heraclitus with an odd central ridge. This is the result of a merger of two or three craters. The large flat floored crater near the center of this image is, Manzinus (100km). Then the large crater on the right edge of this image with the central peak is Vlacq (92km). This should serve to give the outlines.
When processing this image, a montage of two images, I thought I saw an artifact of the knitting process about midway up the terminator. It's a little dotted horizontal line and above the left end the barest outlines of the east walls of two vertically oriented craters still deep in shadow. After examining numerous images of this area taken over the last 10 years that are in the Loudon Observatory Lunar Image Archive (https://www.lpl.arizona.edu/~rhill/moonobs.html) I was finally convinced that these are the regularly spaced tips of a row of peaks and crater walls. On the east (right) end of this line is a large crater in shadow with 'ears' of two smaller craters, also in shadow. The larger crater is Zach (73km) and the adjacent crater to the east (right) is Zach D (32km) while the one to the west is Zach F (28km) crater. That would make the line of peaks west of Zach parts of Zach C (13km) and Zach G (6km) and several other unnamed peaks leading to Deluc D (27km) which is the lower of the two vertical craters and Deluc (49km) itself to the north. Deluc H (26 m) can be just made out above this. So what I at first feared was an artifact was in fact quite real! If I had noticed this at the time I was imaging I would have tried to repeat the observation as the rising sun revealed more of the features themselves. Just another example that the appearance of things on the moon can change quickly on the moon.
A day or two short of the full moon, depending on the libration, on the northwest terminator of the moon you will find a remarkable crater that catches the eye. This is Pythagoras (133km dia.) with beautifully terraced walls and a central peak that casts great shadows across the western side of the crater and the west wall. The extreme near limb presentation of this magnificent crater gives us the opportunity to see just how shallow craters are. When on the terminator near the center of the moon, they look like deep wells but in this case the depth is only 4.8 km or 3.75% of the diameter! Shallow indeed! You can see this for yourself by making a 100mm diameter crater that is only 4mm deep.
The large non-circular crater in front of Pythagoras is Babbage (148km) and to it's left is Oenophiles (70km) and further on is the smaller Markov (43km). To the lower right of Pythagoras is Anaximander (also 70km) and further right is Carpenter (61km). Above Carpenter is the shadow filled Pascal (109km) seen well at this libration.
Below Anaximander is a large shallow circular depression that is the remnant of a once tremendous crater, J. Herschel (160km). On its southern border is Horrebow (26km) and to the left of the the great crater is Robinson (also 26km). Lastly, at the very bottom of this image is the crater Harpalus (41km). Between this crater and Babbage is a squarish area that is named South (111km). Babbage, South, Herschel and Anaximander are the oldest craters in this image being of Pre-Nectarian age, possibly as old as 4.55 billion years. while Harpalus and Carpenter are the youngest being Copernican as old as 1.1 b.y. This is a region worthy of your study on those bright moonlit nights!
Center bottom we have the spectacular crater Tycho (diameter 88km) the center of the largest ray system on the Moon that completely wraps around the globe. This is two days after the terminator passed over this crater and already the sun is high enough to show the rays without washing out some of the topographic details. For orientation purposes, the large dark crater at the top is Pitatus. Just below that are two similar sized craters Gauricus (82km) on the right and Wurzelbauer (90km) and off to the right is a much smaller well defined crater with a fairly dark patchy floor, Hell (34km). To the left of Pitatus and you'll see one of the better double walled craters on the Moon, Hesiodus A (15km) looking like a little bulls-eye target with the small central peak. The parent crater Hesiodus (44km) is above it with a small 5km central crater.
Going back to Tycho we can see one of the larger rays radiating out from the crater about 10 o'clock right off the upper left corner of the image. If you look carefully close in to Tycho you will see a fine trail of secondary crater following along one edge of that ray. This takes some good seeing to spot by eye. Off to the upper right of Tycho you can see a radial spray of fine rays out to the edge of the image. During full Moon you can see these rays wrap around the whole body even in a pair of binoculars..
The whole rim of Mare Nectaris is populated with wonderful features. Here we have the south side with the big scarp Rupes Altai below and left of center stretching from the beautiful crater Piccolomini (90km dia) at bottom going all they way up past the large Catarina (104km) some 495km. You can just barely see another pressure ridge, concentric to Mare Nectaris, running from Catharina down south of the large "U" shaped crater above center, Fracastorius (128km). Unfortunately the nice east-west rima that bisects this crater is just beyond the resolution of this image. But there are many secondary craters on its floor and a splattering of them in the upper left covering Beaumont (54km) a little brother to Fracastorius. These secondaries are likely the ejecta from the Theophilus impact to the north which must have been a fantastic sight!
Normally a more foreshortened feature, at this libration we get a good look into Endymion, the large 125km diameter crater just right of center. As lunar night approaches we see the wonderful shadows crawling across its floor. The two large craters below and to the left (west) are Atlas (90km) and the smaller, younger Hercules (71km) with the satellite crater Hercules G (13km) on its floor. Many observers think these two are much alike but actually they are remarkably different with a smooth flat floor in Hercules and rimae, and roughness on the floor of Atlas. Even the eject is very different in the two with Atlas having a thick ejecta blanket that even covers over a much older crate to the north. Above these two is the teardrop shaped crater Keldysh (34km). Below and to the right of Atlas is a ghost crater seen best at this sun angle, Chevallier (54km), with small satellite crater Chevallier B (13km) contained within its walls. To the right of Chevallier is a flat figure-8 shaped area that is Lacus Temporis some 257km long.
Another smaller mare-like region that lies just north of Endymion is unnamed. North of this regions a hard to trace, ruined crater De La Rue with a 14km crater in the middle, De La Rue J. On its north wall are a couple more craters Strabo (56km) and to its left Thales (32km). At the top of this image is a rather polygonal crater Democritis (41km) and below it another large ghost crater Gartner (105km) opening onto easternmost Mare Frigoris similar to Fracastorius but a much weaker copy. So one way you can remember the layout is that at one END of Mare Frigoris you will find ENDymion!
Outshone by his big brother Copernicus, seen here in the lower left, the sizeable crater, Eratosthenes (diameter 60km) is nevertheless a very interesting crater with nicely terraced walls, a good central peak cluster and a tight herringbone ejecta blanket surrounding the crater. Seen here Eratosthenes forms a southern anchor to the Montes Apenninus. Between Eratosthenes and Copernicus is an eye catching string of secondary craters from the Copernicus impact event. It takes at least a 3" telescope to make them out clearly and the right lighting. At the south end of this string is a large ghost crater, Stadius (70km) which stands between Sinus Aestuum to the east (southeast of Eratosthenes) and Mare Insularum below Copernicus to the southwest.
On the opposite side of Eratosthenes from Stadius is another ghost crater sitting out in Mare Imbrium. This is Wallace (27km) with a more complete rim on the west side than the east. Notice the twin satellite craters below it Eratosthenes A and B (6 & 5 km respectively), small craters to be sure but nowhere near the limit for this image!
Something a little different this time to demonstrate what libration is and how it can be used to advantage. Here we have two images of the region from the crater Janssen looking east. Janssen is the largely ruined 196km diameter polygonal crater near the terminator in the center top of each of the two images in this montage. To the right of the center of this crater is a smaller crater, Fabricius (80km) with an odd mountain range on its floor. To the right of this is the slightly larger Metius (90km) and farther on the trench that is Vallis Rheita some 515km long. Below Janssen are two overlapping craters, the top one being Steinheil (70km) laying on top of Watt (68km).
Notice that in the image on the right you see a lot more terrain between Watt and the limb. This is what a "favorable libration" can do for you and why you need to pay attention to that. A favorable libration on one side of the moon means an unfavorable on the opposite side. On the limb in the image on the right is a portion of Mare Australis which is completely invisible on the left. On the left in the middle of the limb is the highly foreshortened crater Hanno B (36km) but in the July image the crater can be seen plain and clear on the nearside (west) of Mare Australis. These two images clearly show how by picking the right night you can see around the corner, or limb as it were.