Nearest planet to our solar system is detected thanks to wobbling star

Astronomers have found a planet orbiting a star close enough to be seen with the naked eye. It is the nearest planet to be found beyond our own solar system.

Astronomers have found a planet orbiting a star close enough to be seen with the naked eye. It is the nearest planet to be found beyond our own solar system.

The planet is about the size of Jupiter, the biggest of the nine solar system planets, and brings to 42 the number of planets known to be orbiting distant stars.

A team of researchers discovered the existence of the planet by observing the minute "wobble" of its star, Epsilon Eridani, as it was pulled back and forth by the planet's gravitational field.

Epsilon Eridani, which frequently features in science fiction stories, is just 10.5 light years away - meaning that it would take 10.5 years to reach it travelling at the speed of light - which is relatively close in astronomical terms.

It might even be possible to use the Hubble space telescope to see the planet directly, which would be a milestone in the search for extrasolar planets similar to Earth that are capable of supporting life.

"Detecting a planet orbiting Epsilon Eridani - a star very similar to our own sun - is like finding a planet in our own backyard," said William Cochran, an astronomer at the University of Texas in Austin, who led the investigation.

"Not only is this planet near by, it lies 3.2 astronomical units [297m miles] from its central star, roughly the distance from the sun to the asteroid belt in our own solar system," he said.

The planet is, like Jupiter, a "gas giant" and is unlikely to be suitable for life.

"It has a highly eliptical orbit, meaning that temperatures might vary widely in its seven-year journey around Epsilon Eridani, the fifth brightest star in the constellation Eridanus," Professor Cochran said.

"The exciting thing about this discovery is that having a large planet orbiting fairly far out from Epsilon Eridani means there could be room for Earth-like planets in a reasonably stable orbit closer to the star."

The discovery is expectedto be announced at the general assembly of the International Astronomical Union, which meets in Manchester on Monday.

The astronomers found the planet using data sets from four different telescopes with three different measuring techniques, so they are confident of the results.

Because Epsilon Eridani is so bright and one of the 10 nearest star systems, it is easily detectable even without a telescope, Professor Cochran said. "You can go outside at night and point at it and say, 'That star there has a planet around it'," he said.