D'Alembert (crater)

D'Alembert
Clementine mosaic
Coordinates50°48′N 163°54′E / 50.8°N 163.9°E / 50.8; 163.9
Diameter233.55 km (145.12 mi)[1]
DepthUnknown
Colongitude201° at sunrise
FormationNectarian[2]
EponymJean d'Alembert
Oblique Lunar Orbiter 5 image, facing west

D'Alembert is a large lunar impact crater located in the northern hemisphere on the far side of the Moon,[3] to the northeast of the somewhat smaller walled plain named Campbell. 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.[4] Astride the southwest rim of d'Alembert is Slipher.[5] To the north is the crater Yamamoto, and to the south-southwest lies Langevin. This walled plain has the same diameter as Clavius on the near side, making it one of the largest such formations on the Moon.

This formation dates to the Nectarian period of the lunar geologic timescale.[2] As with many lunar walled plains of comparable dimensions, the outer rim of this formation has been worn and battered by subsequent impacts. Besides Slipher, the most notable of these craters is d'Alembert Z intruding into the northern rim. There is also a small crater on the northwest inner wall that has a wide cleft in its eastern side, and a smaller crater along the southeastern inner wall. As eroded as the rim may be, its form can still be readily discerned as a roughly circular ridge line in the lunar terrain.

The interior floor of d'Alembert is a relatively level surface, at least in comparison with the rough terrain that surrounds the crater rim. It is marked with a number of small crater impacts, the largest being d'Alembert G and d'Alembert E toward the eastern rim. In the southwest, the floor is more irregular due to the outer rampart and layers of ejecta from Slipher. A pair of shallow clefts in the floor surface radiate away from this crater, beginning near the midpoint of d'Alembert and reaching half-way toward the inner wall.[6]: 19  Crater chains across Rowland, Carnot, Esnault-Pelterie and Schlesinger craters to the east appear to come from d'Alembert.[5] The infrared spectrum of pure crystalline plagioclase has been identified on the south and central floor, as well as the southeast rim.[7]

This crater is named after French mathematician, physicist, and philosopher Jean d'Alembert (1717–1783).[8] Its designation was officially adopted by the International Astronomical Union in 1970.[1]

Satellite craters

Satellite features of d'Alembert

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to D'Alembert.[9]

d'Alembert[6]: 296  Latitude Longitude Diameter
E 52.8° N 168.2° E 22 km
G 50.9° N 167.5° E 18 km
J 47.5° N 170.4° E 20 km
Z 55.4° N 165.6° E 44 km

D'Alembert G is characterised by an extremely high rockfall density by lunar standards.[10]: 2 

References

  1. 1 2 "d'Alembert". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program. Retrieved 2026-07-21.
  2. 1 2 Byrne, Charles J. (2015). The Moon's Largest Craters and Basins: Images and Topographic Maps from LRO, GRAIL, and Kaguya. Physics and Astronomy. Springer. pp. 8–9. ISBN 978-3-319-22032-1.
  3. ↑ Moore, Patrick (2000). The Data Book of Astronomy. CRC Press. p. 67. ISBN 978-1-4200-3344-1.
  4. ↑ 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.
  5. 1 2 Byrne, Charles J. (2008). The Far Side of the Moon. Springer. pp. 99–101, 142. ISBN 978-1-4899-8806-5.
  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. ↑ 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.
  8. ↑ 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.
  9. ↑ 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.
  10. ↑ Bickel, Valentin Tertius; et al. (June 8, 2020). "Impacts drive lunar rockfalls over billions of years". Nature Communications. 11: 1–7. doi:10.1038/s41467-020-16653-3. eISSN 2041-1723. PMC 7280507. Retrieved 2026-05-15.

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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