Early Earth may have had two moons : Nature News
A previous collision with a smaller companion could explain why the Moon's two sides look so different.Martin Jutzi and Erik Asphaug
Interesting hypothesis. Two moons would have made for some interesting tides, had the proposed second moon survived long enough for the oceans to form.
Earth once had two moons, which merged in a slow-motion collision that took several hours to complete, researchers propose in Nature today.
Both satellites would have formed from debris that was ejected when a Mars-size protoplanet smacked into Earth late in its formation period. Whereas traditional theory states that the infant Moon rapidly swept up any rivals or gravitationally ejected them into interstellar space, the new theory suggests that one body survived, parked in a gravitationally stable point in the Earth–Moon system.
Both satellites would have formed from debris that was ejected when a Mars-size protoplanet smacked into Earth late in its formation period. Whereas traditional theory states that the infant Moon rapidly swept up any rivals or gravitationally ejected them into interstellar space, the new theory suggests that one body survived, parked in a gravitationally stable point in the Earth–Moon system.
A previous collision with a smaller companion could explain why the Moon's two sides look so different.Martin Jutzi and Erik Asphaug
Interesting hypothesis. Two moons would have made for some interesting tides, had the proposed second moon survived long enough for the oceans to form.
