Origin of the Moon-The Collision Hypothesis

In 1871, during his presidential address to the British Association in Edinburgh, William Thompson (later Lord Kelvin) discussed the impact of Earth-like bodies, asserting that "when two great masses come into in space, it is certain that a large part of each is melted" [see (1908, p. 218) for the complete quotation]. Although he did not on to speculate about lunar origin, it must have been remarkable to see of the creators of the bastions of nineteenth century conservative discuss such an apocalyptic event and the debris issuing from it. It equally remarkable that until recently, lunar origin myths have usually around three possibilities (fission, capture, and binary accretion) exclude any important role for giant impacts. The Origin of the Conference held in Kona, Hawaii, on October 13-16, 1984, saw a hypothesis of lunar origin emerge as a strong contender, not of any dramatic new development or infusion of data, but because hypothesis was given serious and sustained attention for the first time. resulting bandwagon has picked up speed (and some have hastened jump aboard). Most significantly, efforts have been made to simulate impacts using three-dimensional hydrodynamic codes on supercomputers. all this effort is promising, a sober reflection on the after two years suggests that a lot more work is needed. It is yet clear whether the collision hypothesis satisfies the observational .