# Theophilus (crater)

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**Theophilus** is a prominent [lunar](/source/Lunar_craters) [impact crater](/source/Impact_crater) that lies between [Sinus Asperitatis](/source/Sinus_Asperitatis) in the north and [Mare Nectaris](/source/Mare_Nectaris) to the southeast. It partially intrudes into the comparably sized crater [Cyrillus](/source/Cyrillus_(crater)) to the southwest. To the east is the smaller crater [Mädler](/source/M%C3%A4dler_(lunar_crater)) and further to the south-southeast is [Beaumont](/source/Beaumont_(crater)).[2] It was named after the 4th-century [Coptic](/source/Coptic_Orthodox_Church_of_Alexandria) [Pope Theophilus I of Alexandria](/source/Pope_Theophilus_I_of_Alexandria).[3]

Theophilus, [Cyrillus](/source/Cyrillus_(crater)) and [Catharina](/source/Catharina_(crater)) form a prominent group of large craters visible on the [terminator](/source/Terminator_(solar)) 5 days after the new moon.

## Description

The rim of Theophilus has a wide, [terraced](https://en.wiktionary.org/wiki/terrace) inner surface that shows indications of landslips. British astronomer [T. W. Webb](/source/Thomas_William_Webb) called this "the deepest of all visible craters".[4] It is 4,200 metres deep with massive walls and has broken into a second formation, [Cyrillus](/source/Cyrillus_(crater)).[5] It was created during the [Eratosthenian](/source/Eratosthenian) period, from 3.2 to 1.1 billion years ago.[6] It has an imposing central mountain, 1,400 metres high, with four summits.[3]

The floor of the crater is relatively flat, and it has a large, triple-peaked central mountain that climbs to a height of about 2 kilometres above the floor. The western peak is designated Psi (ψ), the eastern Phi (φ), and the northern peak is Alpha (α) Theophilus. The western slopes of this ridge are wider and more irregular, whereas the peaks descend more sharply to the floor on the northern and western faces.[7] [Anorthosite](/source/Anorthosite) with a very low [mafic](/source/Mafic) abundance[8] and the infrared spectrum of pure crystalline [plagioclase](/source/Plagioclase)[9] have been detected in these peaks.

The [Apollo 16](/source/Apollo_16) mission collected several pieces of [basalt](/source/Basalt) that are believed to be ejecta from the formation of Theophilus.[10]

## 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 Theophilus.[11]

Theophilus Latitude Longitude Diameter B 10.5° S 25.2° E 8 km E 6.8° S 24.0° E 21 km F 8.0° S 26.0° E 13 km G 7.2° S 25.7° E 19 km K 12.5° S 26.3° E 6 km W 7.8° S 28.6° E 4 km

## References

1. Pike, R. J. (September 1976). "Crater Dimensions from Apollo Data and Supplemental Sources". *The Moon*. **15** (3–4): 463–477. [Bibcode:1976Moon...15..463P](https://ui.adsabs.harvard.edu/abs/1976Moon...15..463P). [doi:10.1007/BF00562253](https://doi.org/10.1007/BF00562253)

1. ["Moon - Theophilus crater region"](http://www.astrosurf.com/antilhue/moon-theophilus.htm). *astrosurf.com*. Retrieved October 16, 2007.

1. *Autostar Suite Astronomer Edition*. CD-ROM. Meade, April 2006.

1. Webb, Rev. T. W. (1962). [*Celestial Objects for Common Telescopes*](https://archive.org/details/celestialobjects00webb). 6th revised ed. Dover. pp. 143, 154–159. Reprint: ISBN 978-0-486-20917-3

1. Moore, Patrick (2001). *On the Moon*. Sterling Publishing Co.. ISBN 0-304-35469-4.

1. [The geologic history of the Moon](https://pubs.er.usgs.gov/publication/pp1348). [USGS](/source/USGS) Professional Paper 1348. By [Don E. Wilhelms](/source/Don_Wilhelms), John F. McCauley, and Newell J. Trask. U.S. Government Printing Office, Washington: 1987. Table 12.2.

1. Rükl, Antonín (1990). *Atlas of the Moon*. [Kalmbach Books](/source/Kalmbach_Books). ISBN 0-913135-17-8.

1. Lemelin, Myriam et al. (May 2015). "Lunar central peak mineralogy and iron content using the Kaguya Multiband Imager: Reassessment of the compositional structure of the lunar crust". *JRG Planets*. **120** (5): 869–887. [doi:10.1002/2014JE004778](https://doi.org/10.1002/2014JE004778)

1. Donaldson Hanna, K. L. et al. (July 2014). "Global assessment of pure crystalline plagioclase across the Moon and implications for the evolution of the primary crust". *Journal of Geophysical Research: Planets*. **119** (7): 1516–1545. [Bibcode:2014JGRE..119.1516D](https://ui.adsabs.harvard.edu/abs/2014JGRE..119.1516D). [doi:10.1002/2013JE004476](https://doi.org/10.1002/2013JE004476)

1. ["Apollo 16 Mission"](http://www.lpi.usra.edu/lunar/missions/apollo/apollo_16/samples/). *Lunar and Planetary Institute*. Retrieved October 16, 2007.

1. Bussey, B. & Spudis, P. (2004). *The Clementine Atlas of the Moon*. New York: [Cambridge University Press](/source/Cambridge_University_Press). ISBN 0-521-81528-2.

## External links

- [Central Peak Bedrock](http://lroc.sese.asu.edu/posts/428), from [LROC](/source/Lunar_Reconnaissance_Orbiter)

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Adapted from the Wikipedia article [Theophilus (crater)](https://en.wikipedia.org/wiki/Theophilus_(crater)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Theophilus_(crater)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.