Traces of a massive planet that nearly destroyed Earth and helped form the Moon billions of years ago have been discovered by scientists.
The giant-impact hypothesis suggests that approximately 4.5 billion years ago a Mars-sized object collided with the newly-formed earth.
This fusion may have helped to create conditions that support life. Scientists also believe a chunk broke off and went on to form the Moon.
They have now analysed traces of the planet, referred to as Theia, on lunar rocks brought back to Earth by Apollo astronauts.
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