Neper is an old

lunar Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...

located near the eastern limb of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

. Due to its location the crater must be viewed during a suitable

libration In lunar astronomy, libration is the wagging or wavering of the Moon perceived by Earth-bound observers and caused by changes in their perspective. It permits an observer to see slightly different hemispheres of the surface at different tim ...

, and is very foreshortened. The crater lies on the south edge of

Mare Marginis Mare Marginis (Latin ''marginis'', the "Sea of the Edge") is a lunar mare that lies on the very edge of the lunar nearside. The selenographic coordinates of this feature are 13.3° N, 86.1° E, and the diameter is 358 km. The name is Latin ...

, to the east of the crater

Jansky The jansky (symbol Jy, plural ''janskys'') is a non- SI unit of spectral flux density, or spectral irradiance, used especially in radio astronomy. It is equivalent to 10−26 watts per square metre per hertz. The ''flux density'' or ''mono ...

. To the northwest across the

is the crater

Goddard Goddard may refer to: People * Goddard (given name) * Goddard (surname) Places in the United States *Goddard, Kansas *Goddard, Kentucky *Goddard, Maryland *Goddard College, a low-residency college with campuses in Vermont and Washington *Goddar ...

. The crater inner walls have worn

terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk a ...

s, 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 John Napier of Merchiston (; 1 February 1550 – 4 April 1617), nicknamed Marvellous Merchiston, was a Scottish landowner known as a mathematician, physicist, and astronomer. He was the 8th Laird of Merchiston. His Latinized name was Ioann ...

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 Neper. The following craters have been renamed by the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

. * Neper G - ''See''

Virchow (crater) 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 ...

. * Neper K - ''See''

Tacchini (crater) 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 ...

References

* * * * * * * * * * * * * {{refend Impact craters on the Moon