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Wednesday, January 28, 1998 Published at 18:24 GMT


A giant planet - or a dwarf?
image: [ Hubble has photographed a planet circling our nearest star ]
Hubble has photographed a planet circling our nearest star

Astronomers in the United States believe they have caught the first glimpse of a planet in another star system.

Using the Hubble space telescope, astronomers in the United States say they have photographed a body circling Proxima Centauri which, at 4.2 light years away, is the closest star to the Earth's sun.

The scientists say Hubble's images are the first ever pictures taken of a planet orbiting another sun.

If the faint point of light spotted close to the star is indeed a planet, it must be enormous - 10 times the size of Jupiter.

But some scientists are speculating that rather than a planet it might be a brown dwarf, which is a failed star too small to shine.

[ image: Hubble plans to explore further]
Hubble plans to explore further
According to New Scientist magazine, the team who made the discovery at the Space Telescope Science Institute in Baltimore are keeping an open mind.

A dozen or so planets have been found outside the Solar System through the gravitational "wobble" they exert on their parent stars.

Baltimore's team leader, Alan Schultz says: "This is different - you can see it."

"Tentative result"

However, Dr Alan Penny, a British astronomer involved in a project to build a powerful new space telescope is taking a cautious view.

"I think it's more likely to be a brown dwarf, but we need more observations," he said.

Based at the Rutherford Appleton Laboratory in Oxfordshire, Dr Penny is involved with a joint European-Nasa bid to launch a powerful space telescope to the edge of the Solar System in 12 to 15 years' time.

[ image: From the Hubble website: a picture perfect Mars]
From the Hubble website: a picture perfect Mars
The instrument, made up of several small telescopes working together, would be able to detect Earth-like planets and examine them for signs of life.

He says the Hubble discovery is important in a field where armies of people are working to make progress.

"This is a step forward, a breakthrough on the way perhaps, but it's a tentative result." he said

Earlier this month, Nasa scientists claimed they had found evidence of a planet orbiting the star Beta Pictoris.

Their claims were based on high resolution pictures obtained from the newly-installed Space Telescope Imaging Spectrograph.

The idea was disputed by the Hubble Space Telescope team.

They said their analysis of their own earlier pictures indicated that planets were only beginning to form around Beta Pictoris, a very young star at between 20 million and 100 million years old.

More observations are planned in the coming months to determine more details about the planet circling Proxima Centauri.

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