Jansen is a lunar

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 crater ...

in the north part of the

Mare Tranquillitatis Mare Tranquillitatis (Latin ''tranquillitātis'', the Sea of Tranquillity or Sea of Tranquility; see spelling differences) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It is the first location on another world to be ...

. The diameter is 24 km. It was named after 17th century Dutch optician

Zacharias Janssen Zacharias Janssen; also Zacharias Jansen or Sacharias Jansen; 1585 – pre-1632) was a Dutch spectacle-maker who lived most of his life in Middelburg. He is associated with the invention of the first optical telescope and/or the first truly ...

. It is located to the east-southeast of the crater Plinius. The rim of Jansen is low and narrow, with a notch along the western edge. The interior is relatively level, which may indicate it has been covered by

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

. To the south-southwest a small but prominent crater lies on the crater floor, halfway between the center and the rim. To the northwest of the rim is 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 wi ...

named Rima Jansen, and to the east are wrinkle ridges in the

mare A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than fo ...

surface. A low ridge runs from near the southeast rim in a southeasterly direction.

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 Jansen. The following craters have been renamed by the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

. * Jansen B — ''See'' Carrel. * Jansen C — ''See'' Beketov. * Jansen F — ''See'' Cajal. File:Jansen L crater AS15-P-9862.jpg, Jansen L File:Jansen R crater AS17-P-2318.jpg, Oblique view of the ghost crater Jansen R ("pancake" at center) and Jansen D crater (lower right)

References

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External links

LTO-60B2 Jansen
— L&PI

topographic map In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but histori ...

* {{cite web , last=Wood , first=Chuck , date=January 15, 2007 , url=http://www.lpod.org/?m=20070115 , title=Stereo Jansen , publisher=Lunar Photo of the Day , access-date=2007-01-15 , url-status=dead , archive-url=https://web.archive.org/web/20070927004315/http://www.lpod.org/?m=20070115 , archive-date=September 27, 2007 Impact craters on the Moon