Copernicus (lunar crater)

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Crater characteristics
Copernicus crater from Apollo 12. NASA photo.
Coordinates	9.7° N, 20.0° W
Diameter	93 km
Depth	3.8 km
Colongitude	20° at sunrise
Eponym	Nicolaus Copernicus

Copernicus is a prominent lunar impact crater located on the eastern Oceanus Procellarum. It is visible using binoculars, slightly northwest of the center of the Moon's Earth-facing hemisphere. South of the crater is the Mare Insularum, and to the south-south west is Reinhold crater. North of Copernicus are the Montes Carpatus, which lie at the south edge of Mare Imbrium. West of Copernicus is a group of dispersed lunar hills.

The crater Copernicus is estimated to be about 800 million years old, the time marking the start of the Copernican era in the Lunar geologic timescale. Due to its relative youth, the crater has received very little erosion and it remains sharp and well-defined.

The circular rim has a discernable hexagonal form, with a terraced inner wall and a 30-km wide, sloping rampart that descends nearly a kilometer to the surrounding maria. There are three distinct terraces visible, and arc-shaped landslides due to slumping of the inner wall as the crater debris subsided.

Most likely due to its recent formation, the crater floor has not been flooded by lava. The terrain along the bottom is hilly in the southern half while the north is relatively smooth. The central peaks consist of three isolated mountainous rises climbing as high as 1.2 km above the floor. These peaks are separated from each other by valleys, and they form a rough line along an east-west axis. Infrared observations of these peaks during the 1980s determined that they were primarily composed of the mafic form of Olivine.

Based on high-resolution images from the Lunar Orbiter V, Terry W. Offield of the U.S. Geological Survey described the crater as having,

...a hummocky crater rim, numerous large slump blocks on the crater wall, and a complex of central peaks. Sets of parallel fractures, aligned with the Lunar structure grid, formed after the crater wall took its present form, but before the smoothest floor materials were emplaced. The smooth floor materials show a swirling pattern of cracks like those seen on terrestrial lava flows. These materials are associated with numerous hills that have summit craters and are probably small volcanoes. Several low places on the rim and wall are partly filled by what appears to be ponded volcanic material, or possibly fluidized impact debris.

The crater rays spread as far as 800 kilometers across the surrounding maria, overlaying rays from the Aristarchus and Kepler craters. The rays are less distinct than the long, linear rays about Tycho crater, instead forming a nebulous pattern with plumy markings. In multiple locations the rays lay at glancing angles, instead of forming a true radial dispersal. An extensive pattern of smaller secondary craters can also be observed surrounding Copernicus, a detail that was depicted in a map by Giovanni Cassini in 1680. Some of these secondary craters form sinuous chains in the ejecta.

The Copernicus crater was given its name by Giovanni Riccioli, an Italian Jesuit who in conformity with church doctrine publicly opposed the heliocentric system revived by Nicolaus Copernicus. Riccioli is quoted as having "flung Copernicus into the Ocean of Storms" (Oceanus Procellarum); nevertheless in naming one of the most prominent craters on the Moon for the man, he may have indicated his true intent. Later the crater was nick-named "the Monarch of the Moon" by Thomas Gwyn Elger.

In 1966 the crater was photographed from an oblique angle by the Lunar Orbiter 2. At the time this detailed image of the lunar surface was termed the 'Picture of the Century'.

[edit] Illustrations

Detail map of Mare Imbrium's features. Copernicus is marked "N".

"Picture of the Century" — close-up of Copernicus interior from Lunar Orbiter 2. NASA photo.

Seen in a telescope at low sun angles, the shadows bring out complex structures within the crater walls

[edit] Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Copernicus crater.

[edit] References

• Pieters, C. M. (January 1, 1982). "Copernicus crater central peak - Lunar mountain of unique composition". Science 215 (2): 59-61.
• Cortright, Edgar M. (1968). “A Closer Look at Copernicus”, SP-168 Exploring Space with a Camera. NASA Langley Research Center, 116.
• Wood, Chuck (2006-10-14). Superb Copernicus. Lunar Photo of the Day. Retrieved on 2006-10-16.
• See the reference table for the general listing of literature and web sites that were used in the compilation of this page.

[edit] See also

• List of craters on the Moon

[edit] External links

• Images of Copernicus crater at LPI moon atlas