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George Emil Palade
George Emil Palade was a Romanian cell biologist and a Nobel Prize winner.
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19 November 2019

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Apollo 12 land at Oceanus Procellarum on the Moon19.11.1969

Wikipedia (24 Dec 2013, 11:34)

Oceanus Procellarum (/oʊˈsiːənəs ˌprɒsɨˈlɛərəm/; Latin for "Ocean of Storms") is a vast lunar mare on the western edge of the near side of Earth's Moon. It is the only one of the lunar maria to be called an "Oceanus" (ocean), due to its size: Oceanus Procellarum is the largest of the maria, stretching more than 2,500 km (1,600 mi) across its north-south axis and covering roughly 4,000,000 km2 (1,500,000 sq mi).


Characteristics

Like all lunar maria, Oceanus Procellarum was formed by ancient basaltic flood volcanic eruptions that covered the region in a thick, nearly flat layer of solidified magma. Unlike the other lunar maria, however, Oceanus Procellarum may or may not be contained within a single well-defined impact basin. Around its edges lie many minor bays and seas, including Mare Nubium and Mare Humorum to the south. To the northeast, Oceanus Procellarum is separated from Mare Imbrium by the Carpathian Mountains. On its north-west edge lies the 32 km wide Aristarchus ray crater, which is considered as the brightest feature on the Near side of the Moon. Also, the more-prominent ray-crater Copernicus lies within the eastern edge of the mare, distinctly with its bright ray materials sprawling over the darker material. On the northern edge of Oceanus Procellarum lies Sinus Roris.


Origin

There are several hypotheses about the origin of Oceanus Procellarum and a related asymmetry between the near and far sides of the Moon. One of the most attractive is that Procellarum was a result of an ancient giant impact on the near side of the Moon. The size of the impact basin has been estimated to be more than 3,000 kilometers, which would make it one of the largest craters in the Solar System. The impact likely happened very early in the moon's history: at the time when magma ocean still existed or just ceased to exist. It deposited 5–30 km of crustal material on the far side forming highlands. If this is the case, all impact related structures such as crater rim, central peak etc. have been obliterated by later impacts and volcanism. One piece of evidence in support of this hypothesis is concentration of incompatible elements (KREEP) and low calcium pyroxene around Oceanus Procellarum.

Other hypotheses include spatially inhomogeneous tidal heating during the Moon's formation and a late accretion of a companion Moon on the far side. The latter postulates that in addition to the present Moon, another smaller (about 1,200 km in diameter) moon was formed from debris of the giant impact. After a few tens million years it collided with the Moon and due to a small collisional velocity simply piled up on one side of the Moon forming what is now known as far side highlands.


Exploration

The robotic lunar probes Luna 9, Luna 13, Surveyor 1 and Surveyor 3 landed in Oceanus Procellarum. The manned Apollo 12 mission also landed in Oceanus Procellarum, with astronauts Pete Conrad and Alan Bean on board. Their landing site, within 300m of Surveyor 3, has become known as Mare Cognitum.

   
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