Lunar highlands

The Moon’s bright, elevated regions, heavily marked by impact craters and composed mainly of ancient anorthositic crust.

Lunar crust: The Moon’s outer solid rocky layer, divided into crustal regions of differing composition and elevation. The highlands are the Moon’s thick, ancient crustal terrain.
Lunar magma ocean: A global or near-global layer of molten rock hypothesized to have covered the early Moon. Crystallization of this ocean is the leading explanation for the highlands’ anorthositic crust.
Giant-impact hypothesis: The leading model that the Moon formed from debris produced by a giant collision with the early Earth. It provides the origin story for the hot early Moon whose crust became the highlands.
Lunar far side: The hemisphere of the Moon that faces away from Earth because the Moon is tidally locked. The far side is dominated by highlands and has far fewer extensive maria than the near side.
Anorthosite: A coarse-grained igneous rock composed predominantly of plagioclase feldspar. Anorthosite makes up much of the highlands’ bright upper crust.
Impact cratering: The formation of craters when asteroids, comets, or other bodies collide with a solid surface. Billions of years of impacts created the highlands’ dense crater record.
Ferroan anorthosite: An ancient lunar rock type rich in plagioclase and containing distinctive iron-bearing minerals. Its lunar samples preserve evidence of early crustal formation from a magma ocean.
Descartes Highlands: A rugged lunar highland region east of Mare Nectaris and the landing site of Apollo 16. Apollo 16 sampled this terrain to investigate highland geology.
Plagioclase feldspar: A group of silicate minerals forming a continuous series from sodium-rich albite to calcium-rich anorthite. Calcium-rich plagioclase dominates the rocks that give highlands their pale appearance.
Lunar basin: A large lunar impact structure, often several hundred kilometers across and sometimes later flooded by lava. Large impacts excavated and reshaped highland crust, leaving major basins within it.

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