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"!
A Humid Place on the Moon
The monster crater here is Gassendi (114km diameter), a landmark for this colongitude on the north shore of Mare Humorum, the "Sea of Moisture". Gassendi was flooded during the same even that created the mare so we only see the tops of what once were magnificent central peaks. The faulted floor is always a enjoyable but I particularly like the detail in the walls of the crater as they catch these early rays of the rising sun. Note the two notches in Gassendi's wall at about the 11 o'clock position. On LROC Quick Map they appear to be to impacts through the mountains giving the appearance at this lighting of being parallel rimae. The nice central peaks and rimae on the floor are provide a rich field for examination. There are 3 main rimae that diverge from a point to the east of the central peaks. Between two of them is a small crater, Gassendi N (3km). The rima on the left side is only 1km wide for much of its length.
Notice the Rimae Mersenius that run from the area west of Gassendi down south along the western shore of Humorum. The smallest craters identifiable on the mare are around 2km diameter as measured with LROC Quick Map. The resolution limit for this aperture on the moon at perigee, which it nearly was this night, is about 1.4km. (see: https://www.lpl.arizona.edu/~rhill/mincrater.html) so how was it possible to see that rima mentioned above? Linear features, especially in a high contrast situations like this where one wall of a canyon is in darkness and the other brightly lit by the Sun allow for such observations.
The “X”
Our best observing weather in southern AZ is when the days are hot, the evenings warm and still. The colongitude was just right so this was a good night to get 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 Aliacensis 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"!
Heading south
A night with the Dynamax6 I just bought as I continue to "shelter in place" during the Coronavirus outbreak. Here we have one of the more identifiable craters on the moon, Clavius (225km diameter) just above center here, containing its impressive arc of smaller craters starting with Rutherfurd (56km) on the southwest rim (lower right) of Clavius and then going through a series of the Clavius satellite craters decreasing in size while curving to the north and east. On the north rim is a crater similar to Rutherfurd. This is Porter (54km). Just outside the wall to the southwest are two similar sized craters. The southernmost one with the relatively smooth floor is Blancanus (109km) and just north and west of it is Scheiner (114km). South of Blancanus is a very flat floored crater, Klaproth (122km) and further south is Casatus (114km). To the left are two more similar craters mostly filled with shadow. The lower one is Kircher (75km) and the one above, with a little central peak is Bettinus (73km).
On the right edge of this image about halfway up is crisp, neat round crater, that is nicely defined. This is Cysatus (51km) and it is adjacent to Gruemberger (97km) on the left or west side. Straight down the right side is of the image leads you pretty close to the south pole of the moon but not at this libration. The moon's north pole is tilted towards us on this night!
Lunar Central
Imagine working on a spacecraft, putting your whole effort into building, launching and guiding of it to its destination (Destination Moon for you old timers) only to lose the telemetry 2 1/2 minutes before the projected touchdown? I've been in a room where that kind of thing happened (on Mars) and everyone looks like a wet dog. It's very depressing. The lunar mission I'm speaking of here is Surveyor 4 which crashed into Sinus Medii very near the Huyginus (10km dia.) and the beautiful squat "V" shaped Rima Huyginus seen in the upper right and Triesnecker (27km) with its complex of rimae in the center. The mean center of the visible disk of the Moon is seen at the "+" symbol. Above it are two similar sized craters, Bruce (7km) on the left and Blagg (5km) on the right. To the left of these are two numbers "4" and "6". The number 4 indicates the supposed crash site of Surveyor 4 on 17 July, 1967. Then just four months later, 10 Nov., 1967, Surveyor 6 successfully landed just a few km to the west of Surveyor 4's resting place indicated here by the number 6 on the image. The LROC orbital imaging spacecraft has even taken image of Surveyor 6 sitting on the surface (attached). I remember as a teenager being disappointed that Surveyor 6 could not see the crashed Surveyor 4 off in the distance but if you think about the curvature of the Moon with its smaller radius than Earth, that simply would not have been possible.
Before leaving this area I have to point out a couple of my favorite craters just north of the landing sites. The larger one is the ruined crater Murchison (60km) Just above Bruce and Blagg, which is open to the east towards the younger, smaller crater Chladni (14km). Then to the west (left) of it is Pallas (51km) with a nice central peak.I always spend some time looking at these when I'm in the area. There's so much to commend this region on the Moon!
East of Deslandres
A spectacular view when the sun first rises on 145km diameter Walter just left of center in this image. It's offset central peak is casting a beautiful long shadow all the way to the western wall. Note the crater in the central peak which is heavily sculpted by impacts. East or right of Walter and a little south is a large irregular depression. This is Nonius listed as 71km diameter though it is anything but circular! North and east are two similar diameter craters. The southern one is Aliacensis (82km) and to the northwest of it is Werner (71km). Notice the beautiful terracing of inner walls of Werner! Above Werner is the raggedy crater Blanchinus (70km) and further up is the shadow filled La Caille (70km). The floor of La Caille is fairly flat with lots of small craters so when the sun rises it rapidly becomes illuminated with all the craterlets splattered about. You can see that starting to happen in this image.
Over on the other side of the image in the upper right corner is the crater Playfair (49km) about 2/3 in the light. One of the twin 3km craters on its floor can be seen just on the edge of the terminator and then straight across from that, on the west side (left) of the crater floor, is a 1.5km crater. South of Playfair is Apianus (65km) and adjacent to it to the west is Krusenstern (49km). forming an isoceles triangle with Apianus and Aliacensis, partly cut of by the corner of the image montage, is the oddly shaped crater Poisson (82km) with the strange ridge running through it. This is fascinating to view as are the curious craters just below it shaped like little paw prints in soft soil!
At the bottom of the image is most of the large crater Stofler (129km) with the delicately streaked floor. The two craters above it are Fernelius (66km) south and Kaiser (54km) above it. Between Kaiser and Poisson is a field of craters of all shapes and sizes up to 20km that make for delightful viewing!