Ring Mountains

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A ring mountain is a large lunar crater with a diameter between 60 km and about 150 km. The eponymous "ring" ( crater rim or crater wall) of such a mountain range is created when a small interplanetary body impacts as an ejection of the highly compressed material. The rock of the Ringgebirge is called lunarite .

Annular structures from asteroid impacts

The relative speed of meteoroids or asteroids is 10 to 70 kilometers per second (30 to 200 times the earth's speed of sound ). Upon impact, the impactor penetrates up to 100 meters into the rock within a few milliseconds. In this brief moment all of its kinetic energy is released. The surrounding material is blown away in a conical shape; at the edge of the depression formed, part of it forms the wall .

Moon crater Theophilus (Apollo 16, NASA)

When a large object or one hits at very high speed , the surface "springs back" and forms a central mountain . When a ball falls into the water, something similar happens: a drop jumps up in the middle. The slope of the inner wall slopes is 20–30 °, that of the outer one is 2 to 3 times flatter. Both depend on the material of the asteroid and the lunar floor, as well as the speed and angle of the impact.

The lunar crater Theophilus shown on the right is a 105 km large circular depression in the floor of the Earth's moon near the visible center of the moon and was formed about 2 billion years ago. It has a wall height of almost 7 km. The terraced interior slopes make it one of the most beautiful objects on the moon. The moon is several dozen of this size ; wider craters (up to 300 km) are classified as whale plains .