A chain of craters on the Moon

Meet Catena Davy.

Seen here are 23 small, similarly sized craters formed in a line. What caused this crater chain?

The crater chain called Catena Davy, as seen by Apollo 12. Credit: NASA

The most plausible scenario for the formation of the crater chain is impact by a comet or an asteroid. Comets and asteroid are weakly held together by their minuscule gravity, and can be ripped apart by the tidal forces of a larger body i.e. the Roche limit. So, a comet or an asteroid on its way to impact the Moon got fragmented by the Moon's tidal forces. Each of those fragmented pieces hit the surface at a slightly different time, due to the rotation of the Moon.

The Moon is known to have many crater chains, called Catenas. Although, not all catenas are formed by the same mechanism as above. Some are formed due to volcanic activity and some due to secondary cratering.

A Catena Davy like crater chain has also been found by NASA's Galileo spacecraft on Jupiter's moon Ganymede. In fact, Jupiter was key to understanding how these types of crater chains form. When the comet Shoemaker-Levy 9 got fragmented under the massive tidal forces of massive Jupiter and impacted it, we realized how crater chains on surface bodies must form. It’s amazing how something that happens on Jupiter can teach us about what caused a feature on the Moon.



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