Riemann (crater)
Encyclopedia
Riemann is a lunar
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 that is located near the northeastern limb of the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, and can just be observed edge-on when libration
Libration
In astronomy, libration is an oscillating motion of orbiting bodies relative to each other, notably including the motion of the Moon relative to Earth, or of Trojan asteroids relative to planets.-Lunar libration:...

 effects bring it into sight. It lies to the east-northeast of the large walled plain Gauss
Gauss (crater)
Gauss is a large lunar crater, named after Carl Friedrich Gauss, that is located near the northeastern limb of the Moon's near side. It belongs to a category of lunar formations called a walled plain, meaning that it has a diameter of at least 110 kilometers, with a somewhat sunken floor and little...

. To the southeast, beyond sight on the far side, is the crater Vestine
Vestine (crater)
Vestine is a heavily eroded impact crater on the Moon's far side, just beyond the northeastern limb. It lies to the southwest of the large walled plain Harkhebi, and to the northwest of the Maxwell–Richardson crater pair....

.

This is a heavily battered and eroded formation that is only a remnant of its former self. The outer rim has been worn away in many places, and now forms an irregular series of ridges in a rough circle. The rim is overlain along the south-southwestern rim by Beals
Beals (crater)
Beals is a lunar impact crater that is located near the eastern limb of the Moon, and lies across the southwestern rim of the crater Riemann. From the Earth the crater is viewed nearly from on edge, and is best seen during favorable librations. To the west is the large walled plain Gauss.This...

, and several smaller craters lie along the western and southeast rim. The most intact portion of the outer wall is along the eastern edge.

The interior floor is a mixture of level terrain mixed with rough ground where impacts have stirred up the surface. It is generally less rough in the eastern half, especially near the center. A small, bowl-shaped crater lies on the floor in the southeastern part of the interior, and the faint remnants of several other lesser craters can be observed in the surface.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Riemann.
Riemann Latitude Longitude Diameter
B 41.6° N 85.2° E 24 km
J 37.4° N 90.2° E 39 km


The following craters have been renamed by the IAU
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

.
  • Riemann A — See Beals (crater)
    Beals (crater)
    Beals is a lunar impact crater that is located near the eastern limb of the Moon, and lies across the southwestern rim of the crater Riemann. From the Earth the crater is viewed nearly from on edge, and is best seen during favorable librations. To the west is the large walled plain Gauss.This...

    .
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