Ammonius (crater)

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Ammonius crater AS16-P-5381.jpg
Slightly oblique view from Apollo 16, facing east
Coordinates8°30′S 0°48′W / 8.5°S 0.8°W / -8.5; -0.8Coordinates: 8°30′S 0°48′W / 8.5°S 0.8°W / -8.5; -0.8
Diameter9 km
Depth1.9 km
Colongitude1° at sunrise
EponymAmmonius Hermiae
Oblique view from Apollo 14, facing west

Ammonius is a bowl-shaped lunar impact crater with a slightly raised rim. It is located on the floor of the walled plain Ptolemaeus, about 30 kilometers northeast of the crater midpoint.

Just to the north on the lava-flooded floor of Ptolemaeus is a relatively prominent "ghost" crater: the discernible buried rim of a pre-existing crater. The diameter of this ghost crater is nearly double that of Ammonius, and is currently identified as Ptolemaeus B.


The crater is named after Greek philosopher Ammonius Hermiae.[1] In the past this crater was identified as Ptolemaeus A, before being named by the IAU in 1976.


  1. ^ "Ammonius (crater)". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.

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