Thomson (crater)

Thomson
	Mare Ingenii, dominated by the crater Thomson
Coordinates	32°42′S166°12′E / 32.7°S 166.2°E Coordinates: 32°42′S166°12′E / 32.7°S 166.2°E
Diameter	117 km
Depth	Unknown
Colongitude	195° at sunrise
Eponym	J. J. Thomson

Last updated August 08, 2019

Thomson is a lunar impact crater that is located within the Mare Ingenii on the far side of the Moon. Just to the northeast is the unusual merged crater formation of Van de Graaff. On the northwest rim of the mare is O'Day, and to the south-southwest is Obruchev on the southern shore of Mare Ingenii.

Lunar craters are impact craters on Earth's Moon. The Moon's surface has many craters, almost all of which were formed by impacts.

An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.

Mare Ingenii is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin, which is of the Pre-Nectarian epoch, which lies in turn in the outer part of the older and much larger South Pole–Aitken basin. The mare material located in Ingenii and the surrounding craters is of the Upper Imbrian epoch. The dark circular feature which dominates this mare is the crater Thomson, with the overflow from Ingenii/Thomson directly to the east. Mare Ingenii is incompletely and thinly covered over much of its expanse with mare lava sheets. The light grey crater to the south of Mare Ingenii is Obruchev.

In the past the crater was flooded by lava, leaving only the outer rim intact. There are gaps in the eastern and western rims, leaving two "half-moon" mountainous formations facing each other across the relatively flat floor. There is a similar lava-flooded crater remnant attached to the southern rim of Thomson. The floor of Thomson has a number of secondary impacts that form short, linear streaks across the surface.

Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Thomson.

Thomson	Latitude	Longitude	Diameter
J	35.9° S	169.6° E	44 km
M	35.7° S	166.0° E	119 km
V	30.7° S	162.2° E	13 km
W	30.2° S	163.3° E	17 km

Related Research Articles

Fracastorius is the 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.

Zupus is the lava-flooded remains of a lunar impact crater. It is located on a southwestern reach of the Oceanus Procellarum, to the northwest of Mare Humorum. To the north-northeast is the flooded crater Billy, and some distance to the southeast is Mersenius. A system of faint rilles named the Rimae Zupus lie to the northwest, following a course to the north-northwest towards the mare.

Zelinsky is a lunar impact crater that is located on the far side of the Moon. It lies nestled along the northern edge of Mare Ingenii, with the oddly shaped crater Van de Graaff along the east rim and the lava-flooded crater Thomson within one crater diameter to the south.

Archytas is a lunar impact crater that protrudes into the northern edge of Mare Frigoris. To the northwest is the comparably sized crater Timaeus, and the smaller Protagoras lies in the opposite direction to the southeast. Further to the southwest, beyond the opposite edge of the mare, is the dark-floored crater Plato.

Bel'kovich is a large lunar impact crater of the form termed a walled plain. The formation has been heavily eroded by a history of subsequent impacts, leaving it reshaped, worn, and the features softened and rounded. Bel'kovich is located along the northeastern limb of the Moon, and so its visibility is subject to libration effects. From the Earth this crater is viewed from the side, making it difficult to view it in detail.

Bowditch is a lunar impact crater that lies on the far side of the Moon, just beyond the eastern limb. It is located on a region of the lunar surface that is brought into view due to libration, but at such times the area is viewed from the edge and so not much detail can be observed. It lies just to the north of the small Lacus Solitudinis lunar mare, between the craters Titius to the southwest and Perel'man to the east-northeast.

Darney is a small lunar impact crater that is located on the region of the Moon where the Mare Nubium joins the Oceanus Procellarum. It was named after French astronomer Maurice Darney. To the south is the lava-flooded crater Lubiniezky. The southern rim of Darney is attached to a series of low ridges that extend to the southwest.

Opelt is the lava-flooded remnant of a lunar impact crater on the Mare Nubium. It lies to the north of a similar formation named Gould and to the northeast of the prominent Bullialdus.

Loewy is a small lunar impact crater that lies along the eastern rim of Mare Humorum, in the southwest part of the Moon's near side. It was named after French astronomer Maurice Loewy. This is a lava-flooded formation that lies to the southwest of the larger, lava-flooded crater Agatharchides. To the southeast is an even larger lava-flooded formation, Hippalus.

Wolf is a lunar impact crater that lies in the south-central part of the Mare Nubium, a lunar mare in the southern hemisphere of the Moon. It lies to the north-northwest of the walled plain Pitatus, and east-southeast of the prominent crater Bullialdus. It is named after the German astronomer Max Wolf.

Elger is a lunar impact crater that lies along the southern edge of Palus Epidemiarum, the Marsh of Epidemics, in the southwest part of the Moon's near side. To the northeast is the flooded crater Capuanus, and farther to the northwest is Ramsden.

Daubrée is a lunar impact crater that is located to the southwest of the Mare Serenitatis, just to the west-southwest of the crater Menelaus in the Montes Haemus range. The small lunar mare Lacus Hiemalis lies along the southwest rim of Daubrée. The crater was named after French geologist Gabriel A. Daubrée. It was previously designated Menelaus S.

Chrétien is a lunar impact crater that is located in the southern hemisphere on the far side of the Moon from the Earth. It lies due south of the Mare Ingenii, one of the few maria on the Moon's far side. The crater lies in the midpoint between the craters Garavito to the west-southwest and Oresme to the east-northeast, both of these being somewhat smaller than Chrétien.

Leibnitz is a huge lunar impact crater that is located in the southern hemisphere on the far side of the Moon. This formation is the same size as Clavius on the near side. It is located to the east-southeast of Mare Ingenii, and is joined to the northeast rim of Von Kármán. Attached to the eastern rim of Leibnitz is Davisson, and intruding into the southeast rim is Finsen. Farther to the west is the large Oppenheimer.

Chevallier is a lunar impact crater that is located in the northeastern part of the Moon's near side, about a crater diameter east-southeast of the prominent crater Atlas. To the south-southeast of Chevallier is the flooded crater Shuckburgh.

Lamb is a lunar crater that lies beyond the southeastern limb on the Moon's far side. It is located in an irregular lunar mare region named Mare Australe, just to the east of the crater Jenner.

Mason is the remains of a lunar impact crater that lies in the northeastern part of the Moon. It is nearly attached to the eastern rim of the flooded crater Plana, and southeast of Bürg. Along the northern rim of Mason is the southern edge of the Lacus Mortis, a small lunar mare. To the south is the larger Lacus Somniorum.

Palmieri is a lunar impact crater that lies to the southwest of the Mare Humorum, in the southwestern quadrant of the Moon's near side. It lies due south of the crater Liebig and east-northeast of the larger Fourier.

Kiess is a lunar impact crater next to the southern border of the Mare Smythii, near the eastern limb of the Moon. It is located to the east of the crater Kästner, and to the north of Dale and Kreiken.

Jules Verne is a large lunar impact crater on the far side of the Moon, named after the French author. It is located to the west-southwest of the Mare Ingenii, one of the few lunar mares on the far side. To the southeast of Jules Verne is the crater Lundmark, while Koch is located to the south-southeast. To the northwest is the large walled plain Pavlov.

References

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Ewen Adair Whitaker was a British-born astronomer who specialized in lunar studies. During World War II he was engaged in quality control for the lead sheathing of hollow cables strung under the English Channel as part of the "Pipe Line Under The Ocean" Project (PLUTO) to supply gasoline to Allied military vehicles in France. After the war, he obtained a position at the Royal Greenwich Observatory working on the UV spectra of stars, but became interested in lunar studies. As a sideline, Whitaker drew and published the first accurate chart of the South Polar area of the Moon in 1954, and served as director of the Lunar Section of the British Astronomical Association.

The National Aeronautics and Space Administration is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research.

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility.

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Mare Ingenii, dominated by the crater Thomson
Coordinates	32°42′S166°12′E / 32.7°S 166.2°E / -32.7; 166.2 Coordinates: 32°42′S166°12′E / 32.7°S 166.2°E / -32.7; 166.2
Diameter	117 km
Depth	Unknown
Colongitude	195° at sunrise
Eponym	J. J. Thomson