* Astronomy

Rupes Recta is a linear fault, or rille, on the Moon, in the southeastern part of the Mare Nubium at 22.1°S 7.8°W. The name is Latin for "Straight Fault", although it is more commonly called the Straight Wall. This is the most well-known escarpment on the Moon, and is a popular target for amateur astronomers.
When the sun illuminates the feature at an oblique angle at about day 8 (after first quarter) of the Moon's orbit, the Rupes Recta casts a wide shadow that gives it the appearance of a steep cliff. The fault has a length of 110 km, a typical width of 2-3 km, and a height of 240-300 m. Thus although it appears to be a vertical cliff in the lunar surface, in actuality the grade of the slope is relatively shallow.
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Rupes Recta from Alcala de Xivert

Rupes Recta- Moon -Daniel Allepuz

Rupes Recta through Lightbridge 16

Ed ~ To locate Rupes Recta look for the large craters Ptolemaeus, Alphonsus, and Arzachel on the terminator just after first quarter phase. South of Arzachel is a large flooded crater. Rupes Recta crosses this ancient crater.