1795 –Pierre-Simon Laplace’s early explanation for the origins of the Solar System offers the first scientific theory of the Moon’s origins. This is known today as the co-accretion hypothesis.
Pierre-Simon Laplace (1749-1827) © Getty Images
1878 – George Darwin puts forward his theory that the Moon split apart from a rapidly spinning young Earth, an idea derived from his mathematical research into tidal forces. This becomes known as the fission theory.
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1952 –Harold Urey publishes the first serious arguments that the Moon may have originated elsewhere in the Solar System and been captured into orbit around Earth at a later stage.
Dr. Harold Urey points at a map of the moon © Getty Images
1975 –William K Hartmann and Donald R Davis suggest that a giant planetesimal impact on the early Earth could have provided the energy to eject material to form the Moon.
1984 – A conference in Kona, Hawaii discusses the origins of the Moon and reaches consensus around the giant impact hypothesis, settling the debate. Many details are still to be resolved, however!