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Why the Moon is shaped like a lemon

30 July 2014 Last updated at 17:54 BST

Scientists have worked out the reasons for the distorted shape of our Moon.

A US team calculated the effect on the shape of the early Moon of tidal and rotational forces.

They say its own spin and the tidal tug of the Earth created a "lemon-shaped" satellite.

Here, lead researcher Ian Garrick-Bethell from the University of California Santa Cruz explains that this shape-shifting occurred when the Moon was mostly liquid beneath a thin outer crust of rock.