An Etymological Dictionary of Astronomy and Astrophysics
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A model for the formation of the Moon according to which the → Moon results from a giant impact. A Mars-sized body (often referred to as → Theia) obliquely collided with the proto-Earth at the mutual escapee velocity. This specific giant impact is often used to represent all giant impacts. A recent advanced version of the canonical model is called → giant impact hypothesis.

→ canonical; → model.