Rupes Altai is an

escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. The terms ''scarp'' and ''scarp face'' are often used interchangeably with ''esca ...

in the lunar surface that is located in the southeastern quadrant of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width ...

's near side. It is named for the Altai Mountains in

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an ...

, and is the most prominent lunar escarpment. The selenographic coordinates of this feature are , and it has a length of about 427 km. The southeastern end of the cliff terminates along the western edge of the crater Piccolomini. It then arcs irregularly towards the north, climbing to heights of nearly a kilometer. The northern end of the arc is an irregular region with no clearly defined terminus, where it brackets the prominent craters

Theophilus Theophilus is a male given name with a range of alternative spellings. Its origin is the Greek word Θεόφιλος from θεός (God) and φιλία (love or affection) can be translated as "Love of God" or "Friend of God", i.e., it is a theoph ...

, Cyrillus, and Catharina. This cliff forms the southwestern rim of the

Nectaris ''Nectaris'', occasionally released as ''Military Madness'', is a series of sci-fi-themed, hex map turn-based strategy games for a variety of systems. The games were developed by Hudson Soft. The company was absorbed by Konami in 2012, and as ...

impact basin. This feature is difficult to locate during the full moon when the sunlight is nearly overhead. It appears as a bright, winding line about five days after the

new moon In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclip ...

, and casts a long, irregular shadow about four days after the

full moon The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic longitudes of the Sun and Moon differ by 180°). This mean ...

, when the sunset

terminator Terminator may refer to: Science and technology Genetics * Terminator (genetics), the end of a gene for transcription * Terminator technology, proposed methods for restricting the use of genetically modified plants by causing second generation s ...

is nearby and the sunlight is arriving at a low angle.

References

External links

Lunar Orbiter 4 Lunar Orbiter 4 was a robotic U.S. spacecraft, part of the Lunar Orbiter Program, designed to orbit the Moon, after the three previous orbiters had completed the required needs for Apollo mapping and site selection. It was given a more general ...

br>image showing most of Rupes Altai
(Lunar and Planetary Institute) * * * * Escarpments on the Moon {{Escarpments on the Moon