The Earth and its two moons (by Lucas)

'Earth may have once had two moons, but one was destroyed in a slow-motion collision that left our lunar current orb lumpier on one side than on the other', scientists say.

Astronomers have long been puzzled by the differences between the side of the moon that always faces the Earth (near side) and the side that always faces away (far side). The topography of the near side is relatively low and flat, while the other is high and mountainous .

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For the theory to work, the smaller moon must have crashed into the larger one at about 4,400 miles (7,081 kilometers) an hour. 

"This is the slowest possible collision the two massive bodies could have if they fell into each other’s gravity," explained study co-author Erik Asphaug,  a planetary scientist at the University of California, Santa Cruz (UCSC). But such a collision would have left the far side splattered with especially hard rocky materials that now form the current lunar highlands.

According to the theory, the two moons coexisted peacefully for about 80 million years, each in its own stable orb, but a gravitational problem may have affected and made them crashed. The moons were the same colour and composition, but one was about three times larger than the other.

Remember that this is just a theory, not necessarily a fact, so, what do you think?

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