by Helen Briggs and Paul Rincon, BBC News – Science & Environment
Astronomers say they have the first evidence of a head-on collision between two planets in a distant star system.
They believe two objects smacked into each other to produce an iron-rich world, with nearly 10 times the mass of Earth.
A similar collision much closer to home may have led to the formation of the Moon 4.5 billion years ago.
The discovery was made by astronomers in the Canary Islands observing a star system 1,600 light years away.