
Rupes Recta is a linear fault on the
Moon, in the southeastern part of the
Mare Nubium at . The name is Latin for ''straight cliff'', 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 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.
To the west of this
escarpment is the crater
Birt
Birt is a surname. Notable people with the surname include:
* Charlie Birt (born 1942), Canadian politician
* Fred Birt (1886–1956), Welsh rugby union player
* Jill Birt (), keyboardist in Australian band The Triffids
* John Birt (footballer) (b ...
, which is about 17 km in diameter. Also to the west is the Rima Birt
rille. At the southern end is a group of hills often called the "Stag's-Horn Mountains", although this name is not officially recognized by the
IAU
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
.
To the northeast is the crater
Alpetragius
Nur ad-Din al-Bitruji () (also spelled Nur al-Din Ibn Ishaq al-Betrugi and Abu Ishâk ibn al-Bitrogi) (known in the West by the Latinized name of Alpetragius) (died c. 1204) was an Iberian-Arab astronomer and a Qadi in al-Andalus. Al-Biṭrūjī ...
, and to the east is
Thebit.
References
External links
*
* – mosaic image of Rupes Recta from the LROC WAC.
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Escarpments on the Moon
{{Escarpments on the Moon