Has The Mystery Of How The Moon Was Formed Finally Been Solved?
The object that smashed into earth to create the moon was far smaller than thought, a new simulation has shown.
Researchers at the Paris Institute of Earth Physics tested over two billion combinations of parameters to try and solve the mystery of how the moon formed.
The key, they concluded, was an impact with a body roughly one-tenth the mass of Earth.
Astronomers have long suspected that the moon was created when a giant protoplanet called Theia struck the newly formed Earth – a theory first put forward in the 1970s.
It says the huge collision created a vast cloud of debris, which coalesced into the moon.
However, until now, astronomers have not been able to explain how this left the moon and Earth chemically identical.
This led to two other ideas, which predicted dramatically different masses for the impact object.
In one, two half-Earths merged to form the Earth-moon system, and in the second, Theia was a small, high-velocity projectile that smacked into a larger and fast-spinning young Earth.
The researchers ran more than 2 billion simulations of the crash, and found an impactor larger than 15 per cent of the mass of Earth, couldn’t produce the chemistry we see in Earth’s mantle, instead leading to a mantle far too rich in nickel and cobalt.
This was known as the giant-impact hypothesis, or the Big Splash.
Now, a simulation created by researchers from Southwest Research Institute in Colorado has found that after this massive impact, there was a long period when leftover mini planets called planetesimals pounded the Earth.
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