Astronomers found two planets that were close matches for Jupiter and Saturn orbiting a star about half the size of our Sun.

Martin Dominik, from St Andrews University in the UK, said the finding suggested systems like our own could be much more common than we thought.

And he told a major meeting that astronomers were on the brink of finding many more of them.

The St Andrews researcher said this planetary system, and others like it, could host terrestrial planets like Earth. It was just a matter of time before such worlds were detected, he explained.

Dr Dominik told BBC News: "We found a system with two planets that take the roles of Jupiter and Saturn in our Solar System. These two planets have a similar mass ratio and similar orbital radius and a similar orbital period.

"It looks like this may have formed in a similar way to our Solar System. And if this is the case, it looks like [our] Solar System cannot be unique in the Universe. There should be other similar systems out there which could host terrestrial planets."

Dr Dominik presented his work at the Royal Astronomical Society's National Astronomy Meeting in Belfast.

Ultimate goal

The newfound planetary system, which orbits the star OGLE-2006-BLG-109L, is more compact than our own and is about five thousand light-years away.

Although nearly 300 extrasolar planets have been identified, astronomers have consistently failed to find planetary systems which resemble our own. Dr Dominik said only 10% of systems discovered so far are known to host more than one planet.

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