Theon Senior is a

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 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 ...

that is located to the northwest of the crater

Delambre Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on th ...

, and south of D'Arrest. It forms a matching pair with Theon Junior, about two crater diameters to the south-southeast. The satellite crater Theon Senior A can be found to the north. Theon Senior is named for

Theon of Smyrna Theon of Smyrna ( ''Theon ho Smyrnaios'', ''gen.'' Θέωνος ''Theonos''; fl. 100 CE) was a Greek philosopher and mathematician, whose works were strongly influenced by the Pythagorean school of thought. His surviving ''On Mathematics Useful fo ...

, a 1st-2nd century Greek mathematician and philosopher.''Autostar Suite Astronomer Edition''. CD-ROM. Meade, April 2006.Moore, Patrick (2001). ''On the Moon''. Sterling Publishing Co.. . This crater is circular and bowl-shaped, with only a small floor at the center of the steeply sloping interior walls. The crater appears relatively young, as it shows little sign of wear due to impacts. The crater is about 18 kilometers in diameter, and the distance from its rim to the floor is 3470 meters. Theon Senior is from the

Eratosthenian The Eratosthenian period in the lunar geologic timescale runs from 3,200 million years ago to 1,100 million years ago. It is named after the crater Eratosthenes, which displays characteristics typical of craters of this age, including a surface ...

period, which lasted from 3.2 to 1.1 billion years ago.

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 Theon Senior. Theon Senior sattelite craters map.jpg, Satellite craters of Theon Senior File:Theon Senior C crater 3083 med.jpg, Theon Senior C

References

External links

Lunar Orbiter 1 The 1966 Lunar Orbiter 1 robotic spacecraft mission, part of NASA's Lunar Orbiter program, was the first American spacecraft to orbit the Moon. It was designed primarily to photograph smooth areas of the lunar surface for selection and verific ...

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showing most of Theon Senior and Theon Senior A
Theon Senior at The Moon Wiki
* {{cite web, last = Wood , first = Chuck , date = December 12, 2006 , url = http://www.lpod.org/?m=20061211 , title = How Deep is That Hole , publisher = Lunar Photo of the Day, url-status=dead, archive-url=https://web.archive.org/web/20110614233616/http://www.lpod.org/?m=20061211, archive-date=June 14, 2011 - includes a couple of craters such as Theon Senior Impact craters on the Moon Eratosthenian