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The Moon's heavily cratered far-side. The origin of the Moon is usually explained by a Mars-sized body striking the Earth, creating a debris ring that eventually collected into a single natural satellite, the Moon, but there are a number of variations on this giant-impact hypothesis, as well as alternative explanations, and research continues into how the Moon came to be formed.
A co-formation of Earth and the Moon together in the primordial accretion disk does not explain the depletion of metals in the Moon. [40] None of these hypotheses can account for the high angular momentum of the Earth–Moon system. [42] The prevailing theory is that the Earth–Moon system formed after a giant impact of a Mars-sized body ...
Artist's depiction of a collision between two planetary bodies. Such an impact between Earth and a Mars-sized object likely formed the Moon.. The giant-impact hypothesis, sometimes called the Theia Impact, is an astrogeology hypothesis for the formation of the Moon first proposed in 1946 by Canadian geologist Reginald Daly.
The formation of new craters is studied in the lunar impact monitoring program at NASA. [4] The biggest recorded crater was caused by an impact recorded on March 17, 2013. [ 5 ] [ 6 ] Visible to the naked eye , the impact is believed to be from an approximately 40 kg (88 lb) meteoroid striking the surface at a speed of 90,000 km/h (56,000 mph ...
The Pre-Nectarian period is defined from the point at which the lunar crust formed, to the time of the Nectaris impact event. Nectaris is a multi-ring impact basin that formed on the near side of the Moon, and its ejecta blanket serves as a useful stratigraphic marker. 30 impact basins from this period are recognized, the oldest of which is the South Pole–Aitken basin.
Geological studies of the Moon are based on a combination of Earth-based telescope observations, measurements from orbiting spacecraft, lunar samples, and geophysical data. . Six locations were sampled directly during the crewed Apollo program landings from 1969 to 1972, which returned 382 kilograms (842 lb) of lunar rock and lunar soil to Earth [8] In addition, three robotic Soviet Luna ...
Thermal state of the Moon at age 100 Ma. [1] Having a mean density of 3,346.4 kg/m 3, [2] the Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and planetary core. This structure is believed to have resulted from the fractional crystallization of a magma ocean shortly after its formation about 4.5 billion ...
The Earth and Moon formed at the same time when the protoplanetary disk accreted The Theia-impact scenario described above The lunar rock samples retrieved by Apollo astronauts were found to be very similar in composition to Earth's crust, and so were likely removed from Earth in some violent event.