Gassendi is a large 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 ...

feature located at the northern edge of

Mare Humorum Mare Humorum (Latin ''hūmōrum'', the "Sea of Moisture") is a lunar mare. The impact basin it is located in is 425 kilometers across. Geology It was not sampled by the Apollo program, so a precise age has not been determined. However, geologi ...

. It was named after French astronomer

Pierre Gassendi Pierre Gassendi (; also Pierre Gassend, Petrus Gassendi; 22 January 1592 – 24 October 1655) was a French philosopher, Catholic priest, astronomer, and mathematician. While he held a church position in south-east France, he also spent much t ...

. The formation has been inundated 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 ...

during the formation of 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 ...

, so only the rim and the multiple central peaks remain above the surface. The outer rim is worn and eroded, although it retains a generally circular form. A smaller crater – Gassendi A – intrudes into the northern rim, and joins a rough uplift at the northwest part of the floor. The crater pair bear a curious resemblance to a diamond ring. In the southern part of the crater floor is a semi-circular ridge-like formation that is concentric with the outer rim. It is in the southern part where the rim dips down to its lowest portion, and a gap appears at the most southern point. The rim varies in height from as little as 200 meters to as high as 2.5 kilometers above the surface. The floor has numerous hummocks and rough spots. There is also a system of

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 ...

s that criss-crosses the floor, named the Rimae Gassendi. The fresh crater Gassendi A is adjacent to Gassendi to the north. Due to its ray system, Gassendi A is mapped as part of the Copernican System.The geologic history of the Moon, 1987, Wilhelms, Don E.; with sections by McCauley, John F.; Trask, Newell J.

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...

Professional Paper: 1348. Plate 11: Copernican System
online
On some older maps the crater Gassendi A was called ''Clarkson'', after the British amateur astronomer and selenographer Roland L. T. Clarkson, but this name is not officially recognized 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 ...

and the name has been removed. Gassendi was considered for a possible landing site during the Apollo program, but was never selected. However, it was imaged at high resolution by

Lunar Orbiter 5 Lunar Orbiter 5, the last of the " Lunar Orbiter series", was designed to take additional Apollo and Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far side. It was also equipped to collec ...

, for this reason. It was also heavily photographed by Apollo 16.

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 Gassendi. Gassendi A crater 5180 med

References

* * * * * * * * * * *

External links

*
Gassendi's Fractures
LROC * * * * {{cite web , last = Wood , first = Chuck , date = December 22, 2007 , url = http://www2.lpod.org/wiki/December_22,_2007 , title = Unnecessary Mystery , publisher = Lunar Photo of the Day , access-date = 2015-11-08 * Lunar Orbiter 5 image (177) o
southern Gassendi crater
* Lunar Orbiter 5 image (178) o
central Gassendi crater
* Lunar Orbiter 5 image (179) o
northern Gassendi crater
and Gassendi A Impact craters on the Moon