Merrill (crater)

Merrill
	Oblique Lunar Orbiter 5 image, facing west
Coordinates	75°12′N116°18′W / 75.2°N 116.3°W Coordinates: 75°12′N116°18′W / 75.2°N 116.3°W
Diameter	57 km
Depth	Unknown
Colongitude	119° at sunrise
Eponym	Paul W. Merrill

Last updated August 08, 2019

Merrill is a lunar impact crater. It is located in the high northern latitudes, on the far side. Less than one crater diameter to the south-southwest of Merrill is the similar Niepce, and to the east along the northern limb is the larger Brianchon.

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.

In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earth's surface. Latitude is an angle which ranges from 0° at the Equator to 90° at the poles. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the precise location of features on the surface of the Earth. On its own, the term latitude should be taken to be the geodetic latitude as defined below. Briefly, geodetic latitude at a point is the angle formed by the vector perpendicular to the ellipsoidal surface from that point, and the equatorial plane. Also defined are six auxiliary latitudes which are used in special applications.

The outer rim of Merrill is worn and the features are softened, but only a few impact craters lie along the edge and inner side. The inner walls are uneven slopes down to the relatively flat interior floor. This surface is marked by several small craterlets, including a pair near the midpoint. The satellite craters Merrill X and Merrill Y form a merged, dual-lobed feature that is attached to the northern outer rim of Merrill.

In the context of spaceflight, a satellite is an object that has been intentionally placed into orbit. These objects are called artificial satellites to distinguish them from natural satellites such as Earth's Moon.

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 Merrill.

A convention is a set of agreed, stipulated, or generally accepted standards, norms, social norms, or criteria, often taking the form of a custom.

Merrill	Latitude	Longitude	Diameter
X	77.0° N	119.2° W	34 km
Y	76.8° N	115.4° W	35 km

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Arrhenius is a lunar impact crater that is located just on the far side of the Moon, near the southwest limb. In this location the vicinity of the crater can be viewed during favorable librations, although it is viewed from on edge. To the south-southeast is the worn crater Blanchard, and De Roy lies further to the west.

Boss is a lunar impact crater that is located along the northeast rim of the Moon's near side. Due to its location, the crater is viewed from the side by observers on the Earth, and its visibility is subject to libration effects.

Casatus is a lunar impact crater that is located near the southern limb of the Moon. The north-northeast rim of the crater overlies a portion of the slightly larger crater Klaproth. Along the western rim, Casatus A intrudes somewhat into the interior, producing an inward-bowing rim. To the southeast of Casatus is Newton.

Chebyshev is a large lunar impact crater that lies in the southern hemisphere on the far side of the Moon. The somewhat smaller crater Langmuir is intruding into the east-southeastern rim of Chebyshev, forming a chain of large craters with Brouwer on Langmuir's eastern rim.

d'Alembert is a large lunar impact crater located in the northern hemisphere on the far side of the Moon, to the northeast of the somewhat smaller walled plain Campbell. Astride the southwest rim of d'Alembert is Slipher. To the north is the crater Yamamoto, and to the south-southwest lies Langevin. This walled plain has the same diameter as Clavius on the near side, making it one of the largest such formations on the Moon.

Carnot is a large crater in the northern part of the Moon's far side. It intrudes into the southern rim of the huge walled plain Birkhoff. To the west-southwest of Carnot is the crater Paraskevopoulos.

Chappell is a lunar impact crater that is located on the far side of the Moon, in the northern hemisphere just to the north of the crater Debye. This feature is located in a heavily bombarded section of the surface, and much of the outer rim of the crater is overlain by many smaller craters. The northern rim in particular has been almost completely disintegrated, while small craters also overlie the rim to the northwest and southeast. What remains of the rim forms a rounded, somewhat irregular edge to the crater depression.

Chandler is a lunar impact crater in the northern hemisphere, on the Moon's far side. It lies to the southeast of the large walled plain D'Alembert, and southeast of the slightly smaller Chernyshev crater.

Fourier is a lunar impact crater that is located in the southwestern part of the Moon's near side, just to the southeast of the crater Vieta. To the northeast is the Mare Humorum. The rim of this crater is roughly circular, but appears oval when viewed from the Earth due to foreshortening.

Kulik is a lunar impact crater that lies on the northern hemisphere of the Moon's far side. The outer rim of this crater has been heavily impacted, particularly along the northern side which is almost entirely overlain by a pair of smaller craters. The southern inner wall is also marked by a cluster of small impacts, and there are small craters across the western rim and notching the eastern inner wall. The interior floor is nearly featureless, but a small central peak rises near the midpoint.

Donner is a lunar impact crater on the far side of the Moon. It is located just to the northeast of the Mare Australe, behind the southeastern limb of the Moon. During favorable librations this part of the lunar surface can be brought into view of the Earth, but the site is viewed from the edge and so not much detail can be seen.

Fowler is a large lunar impact crater that lies in the northern hemisphere on the Moon's far side. It lies to the south-southwest of the crater Esnault-Pelterie, and north of Gadomski. Overlying the eastern rim and intruding into the interior is Von Zeipel.

Frost is a lunar impact crater that is attached to the southern rim of the walled plain Landau, and lies on the far side of the Moon. Just to the east is Petropavlovskiy, and to the northeast along the edge of Landau is Razumov. The crater Douglass is located less than a crater diameter to the west-southwest.

Idel'son is a lunar impact crater that is located on the far side of the Moon. It lies just behind the southern lunar limb, in a region that is sometimes brought into view of the Earth due to libration. Idel'son is situated to the southwest of the huge walled plain Schrödinger.

Pauli is a lunar impact crater that is located on the Moon's far side. It lies about halfway between the lunar equator and southern pole, across the southern rim of the larger walled plain Roche.

Milankovič is a lunar impact crater that is located in the high northern latitudes on the far side of the Moon. Overlapping the southeastern rim is the smaller but more sharply defined crater Ricco. Just to the south is Karpinskiy, and to the north is the prominent Plaskett.

Papaleksi is an impact crater on the far side of the Moon. It lies along the northeastern outskirts of the large crater Mandel'shtam. About 20 km to the north-northeast of Papaleksi is the similar crater Spencer Jones.

References

Andersson, L. E.; Whitaker, E. A. (1982). NASA Catalogue of Lunar Nomenclature. NASA RP-1097.
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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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Oblique Lunar Orbiter 5 image, facing west
Coordinates	75°12′N116°18′W / 75.2°N 116.3°W / 75.2; -116.3 Coordinates: 75°12′N116°18′W / 75.2°N 116.3°W / 75.2; -116.3
Diameter	57 km
Depth	Unknown
Colongitude	119° at sunrise
Eponym	Paul W. Merrill