Diophantus (crater)

Diophantus
Apollo 15 image
Coordinates27°36′N 34°18′W / 27.6°N 34.3°W / 27.6; -34.3
Diameter17.57 km (10.92 mi)[1]
Depth3.02 km (1.88 mi)[2]
Colongitude34° at sunrise
FormationEratosthenian[3]
EponymDiophantus

Diophantus is a small lunar impact crater that lies in the southwestern part of the Mare Imbrium. It forms a pair with the larger crater Delisle to the north.[4] At a similar distance to the west is the smaller Artsimovich crater and the Fedorov feature.[5]

On the lunar geologic timescale, Diophantus is a crater of Eratosthenian age.[3] It is a sharp-edged crater with a wide inner wall and a low central rise. It shows no degradation from subsequent impacts.[6]: 39  High resolution imagery of the inner wall show dark streaks, which originate from material exposed by the impact.[7] A skirt of ejecta spreads across the surrounding mare surface.[8] The cup-shaped impact crater Diophantus C lies prominently near the exterior of the southwest wall.[5]

To the north of Diophantus is the sinuous rille designated Rima Diophantus, named after the crater.[9] It is centered at selenographic coordinates 31°00′N 32°00′W / 31.0°N 32.0°W / 31.0; -32.0, and has a maximum diameter of 201.50 km (125.21 mi).[9] This cleft follows a generally east–west path across the Mare Imbrium.[5] The section nearest Diophantus crater is partially filled with ejecta from that impact.[8]

This formation named after the ancient Greek mathematician Diophantus (unkn-c. A.D. 300). His name was included in the lunar nomenclature of German selenographer Johann H. von Mädler during the 19th century.[10] Its designation was formally adopted by the International Astronomical Union in 1935.[1]

Small craters

High-resolution image of Samir (left) and Louise from Apollo 15 panoramic camera.

Several tiny craters north of Diophantus have been assigned names by the IAU.[5] These are listed in the table below.

Crater Coordinates Diameter Name source
Isabel 28°12′N 34°06′W / 28.2°N 34.1°W / 28.2; -34.1 1 km Spanish feminine name
Louise 28°30′N 34°12′W / 28.5°N 34.2°W / 28.5; -34.2 0.8 km French feminine name
Samir 28°30′N 34°18′W / 28.5°N 34.3°W / 28.5; -34.3 2 km Arabic masculine name
Walter1 28°00′N 33°48′W / 28.0°N 33.8°W / 28.0; -33.8 1 km German masculine name
1 Not to be confused with the large crater Walther in the southern hemisphere, which is misidentified as 'Walter' in some publications

The crater Samir has bright rays that extend for over 70 km.

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 Diophantus.[11]

Diophantus[6]: 297  Latitude Longitude Diameter
B 29.1° N 32.5° W 6 km
C 27.3° N 34.7° W 5 km
D 26.9° N 36.3° W 4 km

The following crater has been renamed by the IAU.

References

  1. 1 2 "Diophantus". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program. Retrieved 2026-08-22.
  2. ↑ Pike, R. J. (September 1976). "Crater Dimensions from Apollo Data and Supplemental Sources". The Moon. 15 (3–4): 463–477. Bibcode:1976Moon...15..463P. doi:10.1007/BF00562253.
  3. 1 2 Wilhelms, Don E.; McCauley, John F.; Trask, Newell J. (1987). The geologic history of the Moon. USGS Professional Paper 1348. Washington: U.S. Government Printing Office. p. 253. doi:10.3133/pp1348.
  4. ↑ Moore, Patrick (2001). On the Moon. Sterling Publishing Co. p. 189. ISBN 978-0-304-35469-6.
  5. 1 2 3 4 "LAC 39" (PDF). Gazeteer of Planetary Nomenclature. Retrieved 2026-08-22.
  6. 1 2 Bussey, B.; Spudis, P. (2004). The Clementine Atlas of the Moon. New York: Cambridge University Press. ISBN 978-0-521-81528-4.
  7. ↑ "Featured Image: Dark Streaks in Diophantus Crater". Lunar Reconnaissance Orbiter. NASA. February 23, 2011. Retrieved 2016-08-22.
  8. 1 2 Oberbeck, V. R.; et al. (July 1975). "Transport and Emplacement of Crater and Basin Deposits". The Moon. 13 (1–3): 9–26. Bibcode:1975Moon...13....9O. doi:10.1007/BF00567505.
  9. 1 2 "Rima Diophantus". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program. Retrieved 2026-08-22.
  10. ↑ Whitaker, Ewen A. (1999). Mapping and Naming the Moon. Cambridge University Press. pp. 120, 219. ISBN 978-0-521-62248-6.
  11. ↑ Grego, P. (2015). "Satellite Crater". In Hargitai, H.; Kereszturi, Á. (eds.). Encyclopedia of Planetary Landforms. New York, NY: Springer. doi:10.1007/978-1-4614-3134-3_328.
  12. ↑ Moore, Patrick; Rees, Robin (2014). Patrick Moore's Data Book of Astronomy (2 ed.). Cambridge University Press. p. 51. ISBN 978-1-139-49522-6.

Sources

  • Price, Fred W. (1988). The Moon Observer's Handbook. Cambridge University Press. ISBN 978-0-521-33500-3.
  • Rükl, Antonín (1990). Atlas of the Moon. Kalmbach Books. ISBN 978-0-913135-17-4.
  • Wlasuk, Peter T. (2000). Observing the Moon. Springer. ISBN 978-1-85233-193-1.
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