An Etymological Dictionary of Astronomy and Astrophysics
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One of the first scientific hypotheses about the formation of the Moon, according to which the Moon formed elsewhere in the solar system and was pulled into a stable orbit by Earth's gravity. Observational facts do not confirm this hypothesis. For example, analysis of rocks from the Apollo landings confirm the Moon is made of similar material and rock as the Earth from about the same time and have almost identical oxygen isotopes in them. Moreover, a captured moon, like Mars' → Phobos and → Deimos do not have a spherical shape. See also → giant impact hypothesis, → fission theory, → co-formation theory.

→ capture; → theory.