Kepler (lunar crater)

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Kepler crater 4138 h1 4138 h2.jpg
Coordinates8°06′N 38°00′W / 8.1°N 38.0°W / 8.1; -38.0Coordinates: 8°06′N 38°00′W / 8.1°N 38.0°W / 8.1; -38.0
Diameter32 km
Depth2.6 km
Colongitude38° at sunrise
EponymJohannes Kepler
Kepler from Apollo 12. NASA photo.

Kepler (Latin Keplerus) is a lunar impact crater that lies between the Oceanus Procellarum to the west and Mare Insularum in the east. To the north is the crater Bessarion, to the east-northeast is the crater Milichius and southeast is the crater Encke.


Kepler is most notable for the prominent ray system that covers the surrounding mare. The rays extend for well over 300 kilometers, overlapping the rays from other craters. Kepler has a small rampart of ejecta surrounding the exterior of its high rim. The outer wall is not quite circular, and possesses a slightly polygonal form. The interior walls of Kepler are slumped and slightly terraced, descending to an uneven floor and a minor central rise.

One of the rays from Tycho, when extended across the Oceanus Procellarum, intersects this crater. This was a factor in the choice of the crater's name when Giovanni Riccioli was creating his system of lunar nomenclature, as Kepler used the observations of Tycho Brahe while devising his three laws of planetary motion. On Riccioli's maps, this crater was named Keplerus, and the surrounding skirt of higher albedo terrain was named Insulara Ventorum.

Due to its prominent rays, Kepler is mapped as part of the Copernican System.[1]

Satellite craters[edit]

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Kepler.

Kepler Latitude Longitude Diameter
A 7.2° N 36.1° W 11 km
B 7.8° N 35.3° W 7 km
C 10.0° N 41.8° W 11 km
D 7.4° N 41.9° W 10 km
E 7.4° N 43.9° W 6 km
F 8.3° N 39.0° W 7 km
P 12.2° N 34.0° W 4 km
T 9.0° N 34.6° W 3 km


  1. ^ The geologic history of the Moon, 1987, Wilhelms, Don E.; with sections by McCauley, John F.; Trask, Newell J. USGS Professional Paper: 1348. Plate 11: Copernican System (online)
  • Wood, Chuck (2006-07-05). "A Smarter Kepler". Lunar Photo of the Day. Archived from the original on 2007-09-27. Retrieved 2006-07-12.