Moons like Earth's could be more common than we thought

[Gerald]

About one in 10 rocky planets around stars like our Sun may host a moon proportionally as large as Earth's, researchers say.

Our Moon is disproportionately large - more than a quarter of Earth's diameter - a situation once thought to be rare.

Using computer simulations of planet formation, researchers have now shown that the grand impacts that resulted in our Moon may in fact be common.

The result may also help identify other planets that are hospitable to life.

A report outlining the results will be published in Icarus.

Last year, researchers from the University of Zurich's Institute of Theoretical Physics in Switzerland and Ryuja Morishima of the Laboratory for Atmospheric and Space Physics at the University of Colorado in the US undertook a series of simulations to look at the way planets form from gas and smaller chunks of rock called planetesimals.

Our own moon is widely thought to have formed early in the Earth's history when a Mars-sized planet slammed into the Earth, resulting in a disc of molten material encircling the Earth which in time coalesced into the Moon as we know it.

http://www.bbc.co.uk/news/science-environment-13609153


Note: 5 June 2011 Last updated at 00:53 GMT