A 110 km fault that can look like a cliff

Feature Profile & Selenographic Data

Feature type

rupes

Coordinates

21.67° S · 7.70° W

Diameter

115.95 km

IAU approval

1961/01/01 00:00:00

LAC quadrangle

LAC-95 · Purbach

Geological Chronicle

Rupes Recta is a linear fault in the southeastern part of Mare Nubium. Its Latin name means “straight cliff”; it is more commonly called the Straight Wall. The Moon’s best-known escarpment is also a popular target for amateur astronomers.

At an oblique angle, sunlight around day 8 of the Moon’s orbit casts a wide shadow, making the fault appear steep. The fault is 110 km long, typically 2–3 km wide, and 240–300 m high. Its slope is relatively shallow.

Birt crater and Rima Birt lie west of the escarpment. A group of hills at its southern end is often called the “Stag’s-Horn Mountains,” a name not officially recognized by the IAU. Alpetragius is northeast of Rupes Recta, and Thebit is to its east.

Chronology & Exploration

1. 2004 Two Lunar Photo of the Day features

   Lunar Photo of the Day listed “Straight Wall” on January 11 and “Obliquely Viewed Fault” on July 30.

2. 2005 “Righteous Recti”

   Lunar Photo of the Day listed “Righteous Recti” on April 13.

3. 2011 LROC WAC mosaic

   A NASA Lunar Reconnaissance Orbiter listing dated February 9 describes a mosaic image of Rupes Recta from the LROC WAC.

Scientific Sources & References

• International Astronomical Union — Rupes Recta — Registry identity, coordinates, diameter, quadrangle, and name origin.
• Wikipedia — Rupes Recta — Localized Wikipedia text and its listed references.

Name Origin

Latin for "straight cliff" (the straight wall).