Today, the giant-impact hypothesis is widely accepted by the scientific community. Early hypotheses included fission from Earth, capture, and co-accretion. Relative concentration of various elements on the lunar surface (in weight %)įor a long period of time, the fundamental question regarding the history of the Moon was of its origin. Neutron spectrometry data from Lunar Prospector indicate the presence of hydrogen (H) concentrated at the poles. Lunar surface chemical composition Compound Carbon (C) and nitrogen (N) appear to be present only in trace quantities from deposition by solar wind. The oxygen content is estimated at 45% (by weight). Among the more abundant are oxygen, iron and silicon. A substantial portion of the lunar surface has not been explored, and a number of geological questions remain unanswered.Įlements known to be present on the lunar surface include, among others, oxygen (O), silicon (Si), iron (Fe), magnesium (Mg), calcium (Ca), aluminium (Al), manganese (Mn) and titanium (Ti). A handful of lunar meteorites have been recognized on Earth, though their source craters on the Moon are unknown. The Moon is the only extraterrestrial body for which we have samples with a known geologic context. 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 In addition, three robotic Soviet Luna spacecraft returned another 301 grams (10.6 oz) of samples, and the Chinese robotic Chang'e 5 returned a sample of 1,731 g (61.1 oz) in 2020. Geological studies of the Moon are based on a combination of Earth-based telescope observations, measurements from orbiting spacecraft, lunar samples, and geophysical data. NASA photo The same image using different color filters Smithsonian Institution Senior Scientist Tom Watters talks about the Moon's recent geological activity.įalse-color image of the Moon taken by the Galileo orbiter showing geological features. The Moon is a differentiated body, with a crust, mantle, and core. In addition to impacts, the geomorphology of the lunar surface has been shaped by volcanism, which is now thought to have ended less than 50 million years ago. It does not have any known form of plate tectonics, it has a lower gravity, and because of its small size, it cooled faster. Instead, the surface is eroded much more slowly through the bombardment of the lunar surface by micrometeorites. The Moon lacks a true atmosphere, and the absence of free oxygen and water eliminates erosion due to weather. The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to " lunar science") is quite different from that of Earth. Oldest to youngest: Aitkenian (pink), Nectarian (brown), Imbrian (greens/turquoise), Eratosthenian (light orange) and Copernican (yellow). Structure and composition of the Moon Geologic map of the Moon, with general features colored in by age, except in the case of maria (in blue), KREEP (red) and other special features.
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