Close up!
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.
South of Heraclitus
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.
North by Northwest
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!
North of Brahe
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.
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On the South Shore
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!
The Ends
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!
Little Brother
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!
LOOKING AROUND THE CORNER
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.
No safe distancing!
This is a crowded highland region on the moon east of Tycho and Clavius. The large crater on the terminator with the great dramatic shadows on is floor is Maginus (168km diameter) with its tiny offset central peaks. Below center is a crater with a pronounced central peak, Lilus (63km) and to the lower right of it is Jacobi (70km) with a bunch of secondary craters on its floor. In the upper right corner of this image is half of the large crater Maurolycus (117km). Notice the crater to the left, Faraday (71km). On the lower left crater wall is a particularly polygonal crater Faraday C (30km) with a curious floor infilled with ejecta from another nearby impact. The concentric depression on the left (west) side of this crater consists of at least 3 merged craters again overlain by ejecta looking like thumbprints in the lunar surface. Moving south from Maurolycus is the crater Barocius (85km) with a curious upper right rim, worthy of some investigation at different illuminations. Going even further south is a smaller crater, Breislak (51km) and just south of that is Baco (71km).
Near the center of the image is another large flat floored crater Cuvier (77km) and just to the left of this crater is the star of the show, a crater called Heraclitus. It is the elongated depression with a long central mountain chain or ridge, a large crater on the north, Licetus (77km) and a smaller crater on the lower end, Heraclitus D (52km). This feature stands out when you run across it with your telescope. It is thought to be several craters merged in some fashion. There is nothing else on the Moon like it. There is a bizarre feature on the floor of Heraclitus D that consists of some deposited material in a mound with fragments of two smaller crater walls that create a spiral form on the southwest quadrant of the crater floor! Lots of strange topography in this area!!
Long Crack
The moon is almost full and it seems like there is little to see. But on the southwest terminator is a grouping of craters that lead us to one of the longest cracks on the Moon. Near the top of this image are two overlapping craters. The one on top is Sirsalis (43km diameter). You will notice a rima running north-south just to the right of it. This is, appropriately enough, Rimae Sirsalis one main rima with several smaller, shorter, thinner ones on the side. The main rima is 309km long, its southern end in shadow here and the northern end of the top of this image. Just to the right of the nameplate on this image is the faintest traces of the upper edge of a crater wall. This is the crater Cruger (48km) with the satellite crater Cruger A (27km) the sharp crater next to the rima. Further on in the same direction is a shallow flat bottomed crater, Fontana (32km). In the lower corner of this image is the half illuminated crater, Henry Freres (43km) and between it and Cruger A is the small crater De Vico (20km). Lastly is the odd little dark feature on the far eastern (right) edge of this image below the black overlap inset. This is Zupus listed as 49km diameter but it was hardly circular. It appears to be a small piece of the Oceanus Procellarum material to the north. In fact it is the flooded remains of an ancient crater who's eastern wall rises 1.3km above the surrounding interior. I'm sure this range would be an impressive sight at sunset from the flooded floor!
East of Nectar
Here we have the east coast of Mare Nectaris. There are some real treats here. The wonderful keyhole shaped crater above center is Gutenberg (77km dia) with smaller Gutenberg C (45km) forming the keyhole shape to the south. To the north are the Rimae Gutenberg looking like three roughly parallel scratch marks heading off to the northwest. Michael Collins got great images of these rimae from the Apollo 11 command module under the file name AS11-42-6313. Then east of Gutenberg is the oddly shaped crater Goclenius (56km) with Rima Goclenius stretching from its north wall some 247 km north to Gutenberg E (28km) the broken crater that intrudes on the northeast wall of Gutenberg. Slightly north and to the west on the terminator, is the shadow filled crater Capella (51km). Very dramatic mountains and formations here can be seen as the sun rises further. To the southwest of Gutenberg is a small but interesting crater Guadibert (34km) just a ring with a central peak here. Further drama is added to this region by the mountainous plateau adjacent to the south of Gutenberg C.
Just south of Goclenius is a mountainous plateau south of Gutenberg C. Further on is a flat floored crater Magelhaens (43km). A couple hundred kilometers south of Magelhaens is the much larger Columbo (78km). The craters between them are satellite craters of these two. But the little dark crater north and east (right) of Columbo is a named crater, Bellot (only 17km!). This whole area is dramatic and always catches the eye when near the terminator.
The Blanchinus “X”
Our best observing weather is when the days are hot, the evenings warm and still. The colongitude was just right so this was a good night toget a look at the famous "X" on the moon. Can you see it on the terminator? It only lasts for and hour or so. Here's how you get there. The area below center of this image is dominated by the two circular pools of darkness that are Aliacensis (82km diameter), lower, and Werner (71km) above. A line between the centers of these two craters lead to the "X" formed by the walls of Blanchinus, La Caille, Purbach and several smaller features. Above Aliacensus and Werner is a nice flat floored crater, Apianus (65km) and further above that is a smaller crater Playfair (49km). Near the top of the image is a pair of craters Azophi (49km) and above it is the irregular Abenezra (43km) with Geber (46km) partially cut off by the edge of this image.
In the lower right of this image is the irregularly shaped Gemma Frisius (90km) overlain by the smaller Goodacre (48km) to the north. Lastly, is the roughly triangular and shadow filled crater Nonius (71km) due south of our first crater landmark, Aliacensis. Enjoy this region but it will take a bit of work and patience to catch the "X"!
