Saturday, July 15, 2017

Lunar 100 Target 15 - The Straight Wall

Photo Details: Celestron 127SLT, ZWO ASI290NC, 1.5x Barlow, stacked from 1 minute video

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Midway across the moon's southern hemisphere, just north of Tycho crater, is an odd sight. On a lunar surface pocked with round craters, a seemingly straight line cuts across one of the dark, smooth cooled lava plains. This is Rupes Recta, or the Straight Wall. It's the best example of a linear fault line to be seen on the moon with a small telescope.

A fault is a crack in an otherwise continuous in a section of rock. In this case, it is thought that the crack resulted from tension in the crust. The rock would have deformed at first, and then broken. One side drops, exposing a rock face called a scarp. The "wall" looks nearly vertical, but is known to have a slope ranging from 7-20 degrees. It is about 110 km/ 68 miles long and 2.5 km/1.5 miles wide. Estimates of its height range from 240m/800 ft to 500m/1640 ft.

The Straight Wall was first recorded in a drawing by Christiaan Huygens in 1686.

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