Neper is an old
lunar impact crater
An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...
located near the eastern limb of the
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
. Due to its location the crater must be viewed during a suitable
libration
In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon that is perceived by observers on the Earth and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see ...
, 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
John Napier of Merchiston ( ; Latinisation of names, Latinized as Ioannes Neper; 1 February 1550 – 4 April 1617), nicknamed Marvellous Merchiston, was a Scottish landowner known as a mathematician, physicist, and astronomer. He was the 8 ...
.
Neper is one of the largest craters of
Nectarian age.
The geologic history of the Moon
USGS
The United States Geological Survey (USGS), founded as the Geological Survey, is an government agency, agency of the United States Department of the Interior, U.S. Department of the Interior whose work spans the disciplines of biology, geograp ...
Professional Paper 1348. By Don E. Wilhelms, John F. McCauley, and Newell J. Trask. U.S. Government Printing Office, Washington: 1987. Table 9-4.
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.
* Neper G - ''See'' Virchow (crater)
Virchow is a small Lunar craters, lunar impact crater that is located on the northwestern interior floor of the prominent crater Neper (crater), Neper. The latter formation lies near the eastern limb of the Moon, along the southern edge of the ...
.
* Neper K - ''See'' Tacchini (crater).
References
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Impact craters on the Moon