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 ''escar ...

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 of ...

's near side. It is named for the

Altai Mountains The Altai Mountains (), also spelled Altay Mountains, are a mountain range in Central Asia, Central and East Asia, where Russia, China, Mongolia and Kazakhstan converge, and where the rivers Irtysh and Ob River, Ob have their headwaters. The m ...

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 area ...

, 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 The House of Piccolomini (pronounced ) is the name of an Italian noble family, Patricians of Siena, who were prominent from the beginning of the 13th century until the 18th century. The family achieved the recognised titles of Pope of the Cathol ...

. 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 Cyrillus, Greek jurist of the 5th century, was a professor in the ancient Law School of Berytus (present-day Beirut), and one of the founders of the oecumenical school of jurists (τῆς οἰκουμένης διδάσκαλοι). This school p ...

, and

Catharina Catharina is a feminine given name, the Dutch and Swedish spelling of the name Catherine. In the Netherlands, people use a great number of short forms in daily life, including ''Carine'', ''Catelijne'', ''Cato'', ''Ina'', ''Ineke'', ''Kaat'', ''Kaat ...

. This cliff forms the southwestern rim of the Nectaris 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 eclipse. ...

, 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 coordinate system, ecliptic longitudes of the Sun and Moon opp ...

, 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, Lunar Orbiter Program, designed to orbit the Moon, after the three previous orbiters had completed the required needs for Project Apollo, Apollo mapping and site s ...

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