Lunar Imagery in 2013

By Damian Peach.

This gallery displays Lunar Imagery obtained during 2013 (dates and times are in the file names.) Some of the text used below is from Wikipedia articles on the respective features.

 

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Fracastorius

A lava-flooded remnant of an ancient lunar impact crater located at the southern edge of Mare Nectaris. To the northwest of this formation lies the crater Beaumont, while to the northeast is Rosse.

The northern wall of this crater is missing, with only mounds appearing in the lunar mare to mark the outline. The lava that formed Mare Nectaris also invaded this crater, so the structure now forms a bay-like extension. The remainder of the rim is heavily worn and covered in lesser impact craters, leaving little of the original rim intact. The maximum elevation of the rim is 2.4 km. The most prominent of these craters is Fractastorius D, which overlies a portion of the western rim.


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Pitiscus

Pitiscus is a lunar impact crater that lies in the southern part of the Moon's near side, just to the northwest of the larger crater Hommel. The crater is worn, but still forms a prominent feature upon the surface. The rim is roughly circular, but appears oval from the Earth due to foreshortening. There is an outward bulge to the south-southeast where the interior has slumped. The remainder of the inner wall still displays terraces, although they are worn and rounded due to erosion.


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Ritter & Sabine

This pair of impact craters are located near the southwestern edge of Mare Tranquillitatis. The two rims are separated by a narrow valley only a couple of kilometers wide. To the northwest is the crater Dionysius, and to the north-northeast are Manners and Arago. This crater is roughly circular but with an irregular outer rim. The inner walls have slumped down towards the floor. The interior is irregular with several low ridges. To the northwest of Ritter is a system of parallel rilles designated Rimae Ritter. These follow a course to the northwest.

Ranger 8 flew over Ritter prior to impact in Mare Tranquilitatis.

Both Sabine and Ritter were originally believed to be calderas rather than impact craters. In To A Rocky Moon, lunar geologist Don E. Wilhelms summarized: "They are identical twins in morphology and size (29-30 km). They lack radial rim ejecta and secondary craters despite their apparent youth. The are positioned at the presumably active edge of a mare. They are even aligned along graben, the Hypatia rilles. Most significant, they lack deep floors recognized since the days of Gilbert as diagnostic of impacts." However, after the Apollo landings were complete, it was realized that "all craters inside basins suffer enhanced isostatic uplift," because "the thin crust and greater heat inside basins lower the viscosity of the craters' substrate, allowing it to reach isostasy with its surroundings more quickly than can other craters.


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Arago

This fairly small lunar impact crater is located in the western part of the Mare Tranquillitatis. It is 26km in diameter. The rim of Arago has a bulge in the western wall. There is a central ridge that runs towards the northern wall. The surface of the mare nearby is marked by wrinkle ridges, most notably to the east and southeast.


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Moretus

This prominent lunar impact crater is located in the heavily cratered highland region near the south pole of the Moon. South of it is the crater Short, while to the north is Cysatus. To the northwest lies Gruemberger, and Curtius is located to the northeast. Due to the location near the lunar limb, the crater appears oblong because of foreshortening.

The rim of the crater has a wide, terraced inner wall, and a complex outer rampart. The floor has been partly resurfaced and is relatively flat. In the middle is a central mountain formation that rises about 2.1 kilometers above the surrounding floor.


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Posidonius

This lunar impact crater that is located on the north-eastern edge of Mare Serenitatis, to the south of Lacus Somniorum. The crater Chacornac is attached to the southeast rim, and to the north is Daniell.

The rim of Posidonius is shallow and obscured, especially on the western edge, and the interior has been overlain by a lava flow in the past. The crater ramparts can still be observed to the south and east of the crater rim, and to a lesser degree to the north. 356mm reflector. ASI120MM.


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Piccolomini

This prominent lunar impact crater located in the southeastern sector of the Moon. The crater Rothmann lies to the west-southwest, and to the south is Stiborius. The lengthy Rupes Altai begins at the western rim of Piccolomini, curving to the northwest. The crater is named after 16th century Italian Archbishop and astronomer Alessandro Piccolomini. It is 88 kilometers in diameter and 4,500 meters deep. It is from the Upper Imbrian period, 3.8 to 3.2 billion years ago. 356mm reflector. ASI120MM.


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Tycho at sunrise

Tycho is a very prominent impact crater located in the southern lunar highlands, named after Tycho Brahe. The surface around Tycho is replete with craters of various differing radii, many overlapping still older craters. Some of the smaller craters are secondary craters formed from larger chunks of ejecta from Tycho.

Tycho is a relatively young crater, with an estimated age of 108 million years, as estimated from samples of the crater rays recovered during the Apollo 17 mission. The crater is sharply defined and free of the wear that affects older craters. The interior has a high albedo that is prominent when the sun is overhead, and the crater is surrounded by a distinctive ray system forming long spokes that reach as long as 1,500 kilometers. Sections of these rays can be observed even when Tycho is only illuminated by earthlight. 356mm reflector. ASI120MM. Souni, Cyprus.


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Schiller is an oddly-shaped impact crater located in the southwest sector of the moon. To the east is the Bayer crater. The rim of Schiller has an elongated shape that is amplified by its proximity to the lunar limb. The long axis lies along a line running northwest-southeast, with the wider girth located in the southeastern half. There is a slight bend in the elongation, with the concave side facing to the northeast. Observers have noted that Schiller appears to be a fusion of two or more craters. It bears a superficial resemblance to the footprint left by a shoe.

The crater rim is well-defined, with a terraced inner wall and a slight outer rampart. At the southeast end, a smaller crater is connected to Schiller by a wide valley. Most of the Schiller crater floor is flat, most likely due to lava flooding. There are some bright patches that are most clearly visible under a high sun angle. A double-ridge lies along the center of the northwest crater floor, forming a nearly linear formation that divides the floor in half. 356mm reflector. ASI120MM. Souni, Cyprus.


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Arzachel is a relatively young lunar impact crater located in the highlands in the south-central part of the Moon, close to the zero meridian. Together with Alphonsus and Ptolemaeus further north the three form a prominent trio of craters. 

The rim of Arzachel shows little sign of wear and has a detailed terrace structure on the interior, especially on the slightly higher eastern rim. There is a rough outer rampart that joins a ridge running from the north rim to southern rim of Alphonsus crater.

The rugged central peak of Arzachel is prominent, rising 1.5 kilometers above the floor, and is somewhat offset to the west with a bowed curve from south to north-northeast. The floor is relatively flat, except for some irregularities in the southwestern quadrant of the crater. There is a rille system named the Rimae Arzachel that runs from the northern wall to the southeast rim. A small crater lies prominently in the floor to the east of the central peak, with a pair of smaller craterlets located nearby. 356mm reflector. ASI120MM. Souni, Cyprus.


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Aristoteles is a impact crater that lies near the southern edge of the Mare Frigoris, and to the east of the Montes Alpes mountain range. To the south of Aristoteles lies the slightly smaller crater Eudoxus, and these two form a distinctive pair. An arc of mountains between these craters bends to the west, before joining the walls.

Observers have noted the crater wall of Aristoteles is slightly distorted into a rounded hexagon shape. The inner walls are wide and finely terraced. The outer ramparts display a generally radial structure of hillocks through the extensive blanket of ejecta. The crater floor is uneven, and covered in hilly ripples. Aristoteles does possess central peaks, but they are somewhat offset to the south. 356mm reflector. ASI120MM. Souni, Cyprus.


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Theophilus, Cyrillus and Catharina

Along with the Ptolemaeus trio, this famous trio of craters is almost as spectacular. Theophilus (at left) is one of the most spectacular impact craters on the Moon and is 100km in diameter. Though well preserved, it is still more than 1 billion years old. Cyrillis is partially overlayed by Theophilus being a rather older formation. Catharina is also an ancient formation overlayed by subsequent impacts. 356mm reflector. ASI120MM. Souni, Cyprus.


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Mare Humboldtianum

(Latin for "Sea of Alexander von Humboldt") is a lunar mare located within the Humboldtianum basin, just to the east of Mare Frigoris. It is located along the northeastern limb of the Moon, and continues on to the far side. Due to its location, the visibility of this feature can be affected by libration, and on occasion it can be hidden from view from Earth. It has a diameter of 273 km. However the surrounding basin extends for a diameter of over 600 km. The walled plain Bel'kovich spills over the northwestern portion of Mare Humboldtianum. 356mm reflector. ASI120MM. Souni, Cyprus.


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Mare Crisium

Mare Crisium (the "Sea of Crises") is a lunar mare located in the Moon's Crisium basin, just northeast of Mare Tranquillitatis. The basin is of the Pre-Imbrian period, 4.55 to 3.85 billion years ago. It is 555 km (345 mi) in diameter, and 176,000 km2 in area. It has a very flat floor, with a ring of wrinkled ridges toward its outer boundaries. Ghost craters (craters that have largely been buried under deposits of other material), are located to the south. 356mm reflector. ASI120MM. Souni, Cyprus.


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J. Herschel at sunrise

J. Herschel is large lunar crater of the variety termed a walled-plain. It is located in the northern part of the Moon's surface, and so appears foreshortened when viewed from the Earth. The southeastern rim of J. Hershel forms part of the edge of the Mare Frigoris lunar mare.

The rim of J. Herschel crater has been heavily eroded, to the point where it is frequently described as "considerably disintegrated". The remaining rim survives as a ring of ridges that have been resculpted by subsequent impacts. The interior floor is relatively level, but irregular and marked by a multitude of tiny impacts. The most notable of these are the satellite craters C, D, K, and L, listed in the table below. 'Horrebow A' is attached to the southern rim of the crater, and is overlapped along its southwest rim by Horrebow. 356mm reflector. ASI120MM. Souni, Cyprus.


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Gassendi at sunrise

A large lunar crater feature located at the northern edge of Mare Humorum. The formation has been inundated by lava during the formation of the mare, so only the rim and the multiple central peaks remain above the surface. The outer rim is worn and eroded, although it retains a generally circular form. A smaller crater 'Gassendi A' is intruding into the northern rim, and joins a rough uplift at the northwest part of the floor. The crater pair bears a curious resemblance to a diamond ring.

In the southern part of the crater floor is a semi-circular ridge-like formation that is concentric with the outer rim. It is in the southern part where the rim dips down to its lowest portion, and a gap appears at the most southern point. The rim varies in height from as little as 200 meters to as high as 2.5 kilometers above the surface. The floor has numerous hummocks and rough spots. There is also a system of rilles that criss-cross the floor, named the Rimae Gassendi. 356mm reflector. ASI120MM. Souni, Cyprus.


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Clavius at sunrise

One of the Moons most famous craters. It is 225km in diameter and peppered by impacts. Its floor is also flooded with ancient lava. As a result on the top of the original central peak is visible. The large craters Rutherfurd (top left) and Porter (bottom left) cut through the wall of this large crater. Clavius was formed more than 3 billion years ago when a large object hit the lunar surface. 356mm reflector. ASI120MM. Souni, Cyprus.


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Aristoteles and Eudoxus

Aristoteles is an impact crater on the southern edge of the Mare Frigoris. It is 87km across and forms a prominent pairing with the nearby Eudoxus crater to the south (37km in diameter.) 356mm reflector. ASI120MM. Souni, Cyprus.


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Ptolemaeus, Aphonsus and Arzachel

Three of the most prominent and famous craters on the Moon. Ptolemaeus (153km), Alphonsus (119km) and Arzachel (96km) form a prominent trio of large craters near the centre of the visible Moon. Alphonsus was the impact site of the Ranger 9 probe in March 1965. The crater contains a complex system of rilles as well as dark halo craters. Arzachel is the youngest of the three craters and also contains a system of rilles, while Ptolemaeus is pitted with countless tiny craters. 356mm reflector. ASI120MM. Souni, Cyprus.


All images copyright Damian Peach. None of the images on this page may be used. amended, or distributed without the consent of the author.