Coordinates | 8°48′N84°30′E / 8.8°N 84.5°E |
---|---|
Diameter | 137 km (85 miles) |
Depth | 2.0 km |
Colongitude | 343° at sunrise |
Eponym | John Napier |
Neper is an old lunar impact crater located near the eastern limb of the Moon. Due to its location the crater must be viewed during a suitable libration, and is very foreshortened. The crater lies on the south edge of Mare Marginis, to the east of the crater Jansky. To the northwest across the Mare Marginis is the crater Goddard.
The crater inner walls have worn terraces, with low rim edges at the northern and southern extremes. The crater floor is dark and flat, with a central peak and several crater impacts near the west rim. The most notable of these is a small crater near the north-northwestern edge.
It is named after the Scottish mathematician, physicist, astronomer and astrologer John Napier.
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Neper.
Neper | Latitude | Longitude | Diameter |
---|---|---|---|
D | 9.2° N | 80.8° E | 40 km |
H | 10.4° N | 78.2° E | 9 km |
Q | 8.0° N | 83.1° E | 12 km |
The following craters have been renamed by the IAU.
Theiler is a tiny lunar impact crater on the eastern lunar limb, in the western Mare Marginis. To the southeast is the prominent walled plain Neper. Due to its location, Theiler is not always visible to observers on the Earth because of the effects of the Moon's libration. Theiler is a circular, bowl-shaped formation of no particular significance.
Descartes is a heavily worn lunar impact crater that is located in the rugged south-central highlands of the Moon. To the southwest is the crater Abulfeda. It is named after the French philosopher, mathematician and physicist René Descartes.
Atwood is a small earth moon impact crater that is located on the Mare Fecunditatis, to the northwest of the prominent crater Langrenus. It forms a triple-crater formation with Naonobu attached to the north rim and Bilharz near the west rim.
Babcock is a lunar impact crater that is located on the far side of the Moon. It was named after American astronomer Harold D. Babcock. It lies on the northeastern edge of Mare Smythii, to the southeast of Mare Marginis. To the south of Babcock is the crater Purkynĕ, and to the east-northeast lies Erro. Babcock is located in a region of the Moon's surface that is occasionally brought into view during favorable librations, although it is seen from the edge and so little detail can be discerned from an observer on the Earth.
Goddard is a lunar impact crater that is located along the eastern limb of the Moon, and so is visible from the edge from Earth. It is best viewed during favorable librations when the orientation of the Moon brings it further into sight. The crater is located in the Mare Marginis, to the northeast of the prominent crater Neper. Ibn Yunus, a crater remnant, is attached to the southeastern rim and is partly overlaid by Goddard. To the northeast is Al-Biruni.
Banachiewicz is a largely degraded lunar impact crater that is located near the eastern limb of the Moon.
Sabatier is a small lunar impact crater that is located near the eastern limb of the Moon, at the southwestern fringes of the Mare Marginis.
Cannon is a lunar impact crater that is located near the east-northeastern limb of the Moon's near side. It lies just to the northwest of the Mare Marginis, and south-southeast of the crater Plutarch. Farther to the east-northeast is Hubble.
Schubert is a lunar impact crater that lies near the eastern limb of the Moon's near side. It is located northwest of the Mare Smythii, and southwest of the prominent crater Neper. Nearly attached to the southern rim is the crater Back.
Virchow is a small lunar impact crater that is located on the northwestern interior floor of the prominent crater Neper. The latter formation lies near the eastern limb of the Moon, along the southern edge of the Mare Marginis. Observation of this area is hindered due to foreshortening, as well as libration effects. It was named after German physician Rudolf Virchow in 1979. Before, this crater had the designation Neper G.
Hubble is a lunar impact crater that lies very near the east-northeastern limb of the Moon. At this location it is viewed almost from the side from Earth, and the visibility of this feature is affected by libration. It lies to the north of the Mare Marginis and northeast of the crater Cannon. About one crater diameter to the north-northeast is Lyapunov.
Jansky is a lunar impact crater that lies along the eastern limb of the Moon. It was named after American physicist Karl Jansky. It lies due east of the larger walled plain Neper, along the southern edge of the Mare Marginis. Due to its location, this crater is viewed from the side from Earth, limiting the amount of detail that can be observed. The visibility is also affected by libration, which can completely conceal this formation from view.
Tacchini is a lunar impact crater on the northwestern edge of the Mare Smythii, near the eastern limb of the Moon. It was named after Italian astronomer Pietro Tacchini. It lies just to the south of the prominent crater Neper, and was designated Neper K before being given its current name by the IAU. To the west-southwest of Tacchini is the crater pair of Schubert and Back.
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.
Dreyer is the remnant of a lunar impact crater on the far side of the Moon. It is located along the eastern edge of the Mare Marginis, about midway between the craters Ginzel to the north and Erro to the south-southeast. It was named after Danish-Irish astronomer John L. E. Dreyer.
Erro is a lunar impact crater that lies beyond the eastern limb of the Moon, on the far side as seen from the Earth. It lies along the eastern fringes of the uneven plain that joins Mare Marginis to the northwest with Mare Smythii to the west-southwest. This part of the surface is sometimes brought into sight of observers on the Earth due to libration. However even at such times not much detail can be seen, as the surface is viewed from the edge.
Firsov is a lunar impact crater on the far side of the Moon. It is located to due south of the crater Lobachevskiy, and to the northwest of Abul Wáfa. The circular rim of this crater has a small outward bulge along the southern edge, and smaller bulges along the western side. The inner walls have slumped to form talus piles along the base. The low-albedo interior floor is nearly level and featureless.
Ginzel is a lunar impact crater that is located on the far side of the Moon, just beyond the eastern limb. It is named after the Austrian astronomer Friedrich Karl Ginzel. It lies at the eastern edge of the Mare Marginis, in a region of the surface that is sometimes brought into sight of the Earth due to libration. To the north-northeast of Ginzel is the crater Popov, and Dreyer lies due south.
Ibn Yunus is the remains of a flooded lunar impact crater. It lies on the far side of the Moon, just past the eastern limb. It can only be viewed from Earth under conditions of favorable libration and lighting, and even then it is seen from the edge. This feature is attached to the east-southeastern outer rim of the flooded crater Goddard. It lies within the Mare Marginis, a lunar mare along the eastern limb.
Möbius is a lunar impact crater that is located on the Moon's far side, beyond the eastern limb and northeast of the Mare Marginis. It lies less than one crater diameter to the northwest of the larger, 90-km-diameter Hertz, and just to the southeast of Popov. To the north of Mobius is the crater chain designated Catena Dziewulski, which takes its name from the crater Dziewulski to the north-northwest.