Posidonius is a

lunar Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...

that is located on the north-eastern edge of

Mare Serenitatis Mare Serenitatis (Latin ''serēnitātis'', the "Sea of Serenity") is a lunar mare located to the east of Mare Imbrium on the Moon. Its diameter is . Geology Mare Serenitatis is located within the Serenitatis basin, which is of the Nectarian ep ...

, to the south of

Lacus Somniorum Lacus Somniorum (Latin ''somniōrum'', "Lake of Dreams") is a basaltic plain located in the northeastern part of the Moon's near side. It is located at selenographic coordinates 37.56° N, 30.8° E, and has a diameter of 424.76 kilometers. The n ...

. It was named after ancient Greek philosopher and geographer

Posidonius Posidonius (; grc-gre, wikt:Ποσειδώνιος, Ποσειδώνιος , "of Poseidon") "of Apamea (Syria), Apameia" (ὁ Ἀπαμεύς) or "of Rhodes" (ὁ Ῥόδιος) (), was a Greeks, Greek politician, astronomer, astrologer, geog ...

of Apamea. The crater Chacornac is attached to the southeast rim, and to the north is Daniell.

Description

The rim of Posidonius is shallow and obscured, especially on the western edge, and the interior has been overlain by a lava flow in the past. The crater ramparts can still be observed to the south and east of the crater rim, and to a lesser degree to the north. There is a smaller, semi-circular rim of a concentric, flooded crater within the main rim, offset towards the eastern edge. There is no central peak, but the floor is hilly and laced with a

rille Rille (German for 'groove') is typically used to describe any of the long, narrow depressions in the surface of the Moon that resemble channels. The Latin term is ''rima'', plural ''rimae''. Typically, a rille can be several kilometers wid ...

system named the Rimae Posidonius. The floor is also slightly bulged due to the past lava uplift, which also likely produced the complex of rilles. The northeast rim is interrupted by the smaller crater Posidonius B. Within the crater rim, offset just to the west of center is another smaller crater Posidonius A. On the Mare Serenitatis surface near Posidonius is a notable system of

wrinkle ridge A wrinkle ridge is a type of feature commonly found on lunar maria, or basalt plains. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features cr ...

s that parallel the nearby shore. These are designated the

Dorsa Smirnov Dorsa Smirnov is a wrinkle ridge system at in eastern Mare Serenitatis on the Moon. It is 222 km long and was named after Soviet geologist Sergei Sergeevich Smirnov by the IAU in 1976.albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

material, its

ray system A ray system comprises radial streaks of fine '' ejecta'' thrown out during the formation of an impact crater, looking somewhat like many thin spokes coming from the hub of a wheel. The rays may extend for lengths up to several times the diameter ...

. This peak was formerly designated Posidonius Gamma (γ). Posidonius Gamma was first observed by the lunar cartographer Julius Schmidt in 1867, who noted the similarity to the bright patch surrounding the crater

Linné Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Posidonius.

References

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External links

Lunar Reconnaissance Orbiter The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions t ...

pages with images: ** - especially on the rille Rimae Posidonius ** **{{cite web , url = http://lroc.sese.asu.edu/posts/269 , title = Rimae Posidonius , author = Ostrach L. , publisher = NASA/GSFC/LROC, School of Earth and Space Exploration, Arizona State University , date = 2010-12-01 , archive-url = https://web.archive.org/web/20180531105109/http://lroc.sese.asu.edu/posts/269 , archive-date = 2018-05-31 , url-status = live Impact craters on the Moon