Rupes Recta

  • Don SpainEmail author
Part of the Astronomer's Pocket Field Guide book series (ASTROPOC)


Rupes Recta is the most famous fault on the lunar surface. Known commonly as the Straight Wall, it is where the surface has cracked and slipped below the eastern surface. It is about 70 miles in length and ends near a 3 mile crater at its northern terminus. At its southern end there is a grouping of hills. It doesn’t take a lot of imagination to visualize these hills as the handle and hilt of a sword and the Straight Wall as the blade of the sword. The best time to see this fascinating fault is 1 day after first quarter. It is then easily visible in my 2.4 inch refractor. It looks like the fault is a sheer drop, but in reality it slopes downward. Published estimates give a range from 40° to 7°. I am inclined to believe that it slopes no more than a gentle 10°. My personal estimate of the height is 800–1,200 feet. This formation is a must show at any public observation and to a beginning lunar observer.

Thebit (35 miles) is the large crater east of the Straight Wall. It is a deep crater with terraced walls that are almost 2 miles high. There is a very prominent 12 mile crater on its western rim. That crater in turn has a 7 mile crater on its western rim. Thebit’s floor is rough with hills and crests.


Good Condition Good Time Lunar Surface Rare Occasion Easy Target 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Louisville Astronomical SocietyLouisvilleUSA

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