A PLANET that measures less than three miles across has been named after an eminent Durham astronomer in recognition of his research work.

The minor planet, or asteroid, which until now has been known only by its number (10979) 4171 T-2, has been named after Professor F Richard Stephenson, a researcher in the Department of Physics at Durham University.

The asteroid, which lies between Mars and Jupiter and orbits the sun, is to be known internationally as Fristephenson.

It was first discovered in 1973, but has been named only now, in accordance with astronomical guidelines which allow prominent figures within the field to be recognised for their work.

Prof Stephenson, who lives in Newcastle, was nominated by Daniel Green, a senior researcher at Harvard University and a part-time student at Durham, for his research in the study of ancient and medieval astronomical observations to improve knowledge of the Earth's rotation, and the study of supernovae and comets.

The pair are both members of the International Astronomical Union and meet regularly at international conferences.

Fristephenson, which is about two-and-a-half miles in diameter, takes three years and ten months to orbit the Sun.

It is an average of 230 million miles away from the Sun, compared to the Earth, which is an average of 93 million miles away.

Professor Stephenson said: "Something like this is reasonably rare and it is something of a honour, so I am naturally thrilled.

"I have the knowledge now that this little planet going round the sun will be named after me for time immemorial.

"It was about six months ago that I was told my name was being put forward, but I never thought any more about it."

He added: "Unlike some minor planets, Fristephenson does not cross the Earth's orbit, so it presents no danger to us here on Earth.

"It is only actually a chunk of rock about two or three miles across. It would be pretty cold on there, about 100 degrees below zero."