Theon Junior (crater)

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Theon Junior
Theon Sr Theon Jr craters 4090 h1.jpg
Lunar Orbiter 4 image of Theon Senior (top) and Theon Junior (bottom)
Coordinates 2°18′S 15°48′E / 2.3°S 15.8°E / -2.3; 15.8Coordinates: 2°18′S 15°48′E / 2.3°S 15.8°E / -2.3; 15.8
Diameter 17 km
Depth 3,580 m
Colongitude 344° at sunrise
Eponym Theon of Alexandria
Oblique view of Theon Senior (top) and Theon Junior (bottom) from Apollo 16

Theon Junior is a lunar impact crater that is located just to the west-southwest of the crater Delambre. Other nearby prominent crater is Taylor to the south.

It forms a matching pair with Theon Senior, only a couple of crater diameters to the north-northwest. The crater is circular and bowl-shaped, with a small floor at the bottom of the high, sloping interior walls. It is named for Theon of Alexandria, a 4th-century Greek astronomer and mathematician. The crater is from the Eratosthenian period, which lasted from 3.2 to 1.1 billion years ago. It is 17 kilometers in diameter and the difference in height at its rim and its deepest part is 3,580 meters.[1][2]

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 Theon Junior.[3]

Latitude Longitude Diameter
B 2.1° S 13.3° E 8 km
C 2.3° S 14.7° E 4 km


  1. ^ Autostar Suite Astronomer Edition. CD-ROM. Meade, April 2006.
  2. ^ Moore, Patrick (2001). On the Moon. Sterling Publishing Co.. ISBN 0-304-35469-4.
  3. ^ Bussey, B.; Spudis, P. (2004). The Clementine Atlas of the Moon. New York: Cambridge University Press. ISBN 0-521-81528-2.