Planets found closer to Earth

Scientists believe they have discovered planets orbiting a star only eight light years away from the Earth. Previously, it was believed that the nearest star, apart from the Sun, which had planets in orbit, lay at least 40 light years away.

The star, Lalande 21185, a dim "red dwarf", is the fourth closest to the Earth and is so close to the Sun that it is a neighbour in galactic terms. It is 200 times less bright than the Sun and has only one-third of its mass. The new research suggests that it has two planets orbiting it - the closest that such bodies have been found.

"We're pretty sure that there's something there, but it's a little early to say exactly what," according to George Gatewood, who told a meeting this week of the American Astronomical Society in Wisconsin of his discovery of the planets.

The analysis suggests that there are two planets orbiting the star, each of which is roughly the size of Jupiter - the heaviest planet in our solar system. Professor Gatewood calculated that one circles Lalande 21185 every 30 years at a distance of about 900 million miles (about the same distance as Saturn) and the other lies closer, a few hundred million miles from the star, orbiting it every six years.

Other stars have been pinpointed as having orbiting planets, but never so close. Last October, astronomers reckoned they had detected one around 51 Pegasi, 40 light years away. In January they spotted variations in the behaviour of Beta Pictoris, 50 light years away.

"These are the first ones that are really like our solar system," said Steve Maran, an astronomer at Nasa's Goddard Space Flight Center in Maryland. Professor Gatewood found the planets by tracking the star's motions on the sky down to the object's tiniest twitch.

The planets' existence has not been confirmed by independent astronomers, but Mr Maran said the results suggest planets are the most likely explanation for the star's movements.