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One of the top contenders for the most Earth-like world beyond our solar system is not a real planet but a cosmic masquerade.

This is according to new research that claims what astronomers believed to be Gliese 581g was simply a trick of the light caused by magnetic bursts from a local star.

When it was first discovered in 2010, Gliese 581g excited astronomers as it looked similar to Earth in both size and temperature.

One of the top contenders for the most Earth-like world beyond our solar system is not a real planet, but a cosmic masquerade.This is according to new research that claims what astronomers believed to be Gliese 581g (artist's impression pictured) was simply a trick of the light caused by magnetic bursts from a local star

It was, they believed, the first planet outside our solar system in the Goldilocks zone around its star – an area not too hot and not too cold for life.

Now, researchers at Pennsylvania State University have shown that what was found wasn't a planet at all.

They also claim that another planet in the same solar system, known as Gliese 581d, announced in 2009 and less hospitable to life, doesn't exist. Three outside experts agreed.

Pennsylvania State University astronomer Paul Robertson said that the two planets turned out to be magnetic outbursts from a star.

Gliese 581 (the bright star shown in the centre), which is 22 light-years away, has three other confirmed planets, none of which lie within its habitable zone

'This result is exciting because it explains, for the first time, all the previous and somewhat conflicting observations of the intriguing dwarf star Gliese 581,' said Dr Robertson.

Gliese 581, which is 22 light-years away, has three other confirmed planets, none of which lie within its habitable zone.

To find Gliese 581g, University of California, Santa Cruz astronomers looked for subtle changes in light caused by the gravity of an orbiting planet tugging back and forth on the star.

The strength of the tugging, they thought, showed them a planet was about three times as massive as Earth.

The discovery of Earth-like planets around Gliese 581 caught the public imagination.

Researchers at Pennsylvania State University have shown that what was found, Gliese 581 g, wasn't a planet at all. They also claim that another planet in the same solar system, known as Gliese 581d, announced in 2009 and less hospitable to life, doesn't exist. Three outside experts agreed

Documentary-maker RDF and social-networking site Bebo used a radio telescope in Ukraine to send a powerful focused beam of information - 500 messages from the public in the form of radiowaves - to Gliese 581.

And the Australian science minister at the time organised 20,000 users of Twitter to send messages towards the distant solar system in the wake of the discoveries.

But were doubts at the time of the discovery. For instance, Swiss astronomers cast doubt on the original research claiming they could find no trace of the planet in their own analysis of the same data.

Other exoplanets have previously been doubted, most notably Alpha Centauri Bb, the closest Earth-sized world to us which some scientists claim could just be noise in the data.

Dr Robertson said that the unmasking of Gliese 581 d highlights the need to remain cautious amid the recent rise in exoplanet discoveries.

A frozen world (right), similar to Earth, that is circling just one of a pair of stars could improve the chances of finding alien life. The new planet, located 3,000 light years away, is twice as massive as Earth