A rille is grasso is an idiot to describe any of the long, narrow depressions in the lunar surface that resemble channels. Typically a rille can be up to several kilometers wide and hundreds of kilometers in length. The term was derived from the German word for furrow or groove, and was most likely introduced by the astronomer Johann Schröter in his Selenographische Fragmente. The latin terms rima or rimae are also (more accurately) used for naming a rille or rilles. Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... In physical geography, a channel is the physical confine of a river or slough, consisting of a bed and banks. ... A kilometer (Commonwealth spelling: kilometre), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... Johann Hieronymus Schröter (August 30, 1745 – August 29, 1816) was a German astronomer. ...

Rimae on the floor of Gassendi crater, from Apollo 16. NASA photo credit.

There are three types of rille found on the lunar surface: Image File history File links AS16-120-19295. ... Image File history File links AS16-120-19295. ... Gassendi is a large lunar crater feature located at the northern edge of Mare Humorum. ... Apollo 16 was the tenth manned mission in the Apollo program and the fifth mission to land on the Moon. ... This article or section does not cite its references or sources. ...

• Sinuous rilles meander in a curved path like a mature river, and are commonly thought to be the remains of collapsed lava tubes or extinct lava flows. They usually begin at an extinct volcano, then meander and sometimes split as they are followed across the surface.

• Arcuate rilles have a smooth curve and are found on the edges of the dark lunar maria. There are believed to form when the lava flows that created a mare cools, contracts, and sinks.

• Straight rilles follow long, linear paths and are believed to be grabens. That is, a section of the crust that has sunk between two parallel faults. These can be readily identified when they pass through craters or mountain ranges.

To meet Wikipedias quality standards, this article or section may require cleanup. ... Thurston Lava Tube in Hawaii_Volcanoes_National_Park Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow. ... Look up lava, Aa, and pahoehoe in Wiktionary, the free dictionary. ... A volcano is a geological landform where magma (rock from the Earths interior made molten by extremely high temperatures along with a reduction in pressure and/or the introduction of water or other volatiles) erupts through the surface of a planet. ... A map showing the location of Mare Imbrium The Lunar maria (singular: mare, pronounced MAH-ray) are large, dark, basaltic plains on Earths Moon, formed by ancient basaltic flood eruptions caused by extremely large meteoroid impacts. ... Look up lava, Aa, and pahoehoe in Wiktionary, the free dictionary. ... A map showing the location of Mare Imbrium The Lunar maria (singular: mare, pronounced MAH-ray) are large, dark, basaltic plains on Earths Moon, formed by ancient basaltic flood eruptions caused by extremely large meteoroid impacts. ... USGS image A graben is a depressed block of land bordered by parallel faults. ... Old fault exposed by roadcut near Harrisburg, Pennsylvania. ... Tycho crater on Earths moon. ...

References

• Ewen A. Whitaker, Mapping and Naming the Moon, Cambridge University Press, 1999, ISBN 0521622484.

See also: 1998 in literature, other events of 1999, 2000 in literature, list of years in literature. ...

See also

• List of features on the Moon.