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// Workers AI · dad joke modeWhy Birkhoff crater so calm? It's filled in.

From Wikipedia, the free encyclopedia
Birkhoff
Clementine mosaic
Coordinates58°42′N 146°06′W / 58.7°N 146.1°W / 58.7; -146.1
Diameter329.81 km (204.93 mi)[1]
Depth4.76 km (2.96 mi)[2]
Colongitude156° at sunrise
FormationPre-Nectarian[3]
EponymGeorge D. Birkhoff

Birkhoff is a giant lunar walled plain that is located on the far side of the Moon, in the northern hemisphere.[4] This class of formation is known as a peak ring basin, which has a single interior topographic ring or a discontinuous ring of peaks with no central peak.[5] It is an ancient impact site that has been heavily eroded, and the surface reshaped by multiple craters in the interior and along the rim. The outer wall is bordered by the craters Carnot to the south, Rowland along the west rim, and Stebbins, which is intruding into the north. Just to the northeast is van't Hoff.[6]

This formation is one of the oldest lunar basins, dating to the Pre-Nectarian epoch of the lunar geologic timescale.[3] What remains of the perimeter is now a rugged sloping rise along the inner wall, and the rim has been worn down until it is level with the irregular external terrain. The rim is pock-marked by small craters of various dimensions.[7]: 19 

Within the crater are several craters that are notable in their own right. Along the northwest inner rim is the eroded Birkhoff X, while due south in the southwest floor is Birkhoff Q. The later is joined by a low ridge to the double crater formation of Birkhoff K and L in the eastern half of the crater. In the northern interior are the smaller but relatively young Birkhoff Y and Z. The remainder of the floor is flat in places, with rough sections and many tiny craterlets.[7]: 19  The infrared spectrum of pure crystalline plagioclase has been identified on the southern floor.[8]

This crater was named after American mathematician George D. Birkhoff (1884–1944).[9] Its designation was formally adopted by the International Astronomical Union in 1970.[1]

Satellite craters

[edit]
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 Birkhoff.[10]

Birkhoff[7]: 293  Latitude Longitude Diameter
K 57.8° N 144.3° W 58 km
L 56.6° N 144.8° W 37 km
M 54.7° N 144.8° W 23 km
Q 56.6° N 150.8° W 43 km
R 57.5° N 153.0° W 27 km
X 62.1° N 149.7° W 77 km
Y 59.9° N 146.6° W 25 km
Z 61.3° N 145.3° W 30 km

Birkhoff Z dates to the Copernican period.[4]

[edit]

References

[edit]
  1. 1 2 "Birkhoff". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
  2. ↑ Williams, Kevin K.; Zuber, Maria T. (January 1998). "Measurement and Analysis of Lunar Basin Depths from Clementine Altimetry". Icarus. 131 (1): 107–122. Bibcode:1998Icar..131..107W. doi:10.1006/icar.1997.5856.
  3. 1 2 Kirchoff, M. R.; et al. (2011). Reevaluation of lunar impactor population evolution: preliminary results from crater distributions on diverse terrains (PDF). 42nd Lunar and Planetary Science Conference. Retrieved 2026-06-07.
  4. 1 2 Byrne, Charles J. (2008). The Far Side of the Moon. Springer. p. 168. ISBN 978-1-4899-8806-5.
  5. ↑ Baker, David M. H.; et al. (August 2011). "The transition from complex crater to peak-ring basin on the Moon: New observations from the Lunar Orbiter Laser Altimeter (LOLA) instrument". Icarus. 214 (2): 377–393. Bibcode:2011Icar..214..377B. doi:10.1016/j.icarus.2011.05.030.
  6. ↑ "LAC 19" (PDF). Gazeteer of Planetary Nomenclature. Retrieved 2026-06-07.
  7. 1 2 3 Bussey, B.; Spudis, P. (2004). The Clementine Atlas of the Moon. New York: Cambridge University Press. ISBN 978-0-521-81528-4.
  8. ↑ 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. doi:10.1002/2013JE004476.
  9. ↑ Menzel, D. H.; et al. (1971). "Report on Lunar Nomenclature by the Working Group of Commission 17 of the IAU". Space Science Reviews. 12 (2): 136–186. Bibcode:1971SSRv...12..136M. doi:10.1007/BF00171763. S2CID 122125855.
  10. ↑ 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.
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