Celestron Neximage and Registax
C8 with 2x Barlow

Rupes Recta is a linear fault on the Moon, in the southeastern part of the Mare Nubium. The name is latin for "Straight Fault", although it is more commonly called the Straight Wall. This is the most well-known escarpment feature 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 of the lunar orbit, the Rupes Recta casts a wide shadow that gives it the appearance of a steep cliff.

June 26, 2007