Giant asteroid enters record books

By BBC News Online's Helen Briggs

A giant space rock has entered the record books as the largest known asteroid.

European astronomers confirmed on Friday that a distant object seen circling our star near Pluto had broken a 200-year-old record.

The previous incumbent was the asteroid Ceres, which was discovered in 1801.

People who believe that Pluto is just a minor planet will have more proof now

Lars Lindberg Christensen of the Hubble European Space Agency

The new object is much bigger, about half the size of Pluto, and is very distant from the Earth.

The asteroid was first spotted in May by astronomers at the Cerro Tololo Observatory, Chile.

Follow-up studies put its size at 1,200 kilometres or more across.

Major and minor

The asteroid is of great interest to astronomers not just because of its massive size but because it could shed light on the debate over Pluto's classification as a major planet.

Some astronomers believe that Pluto, the smallest planet in the Solar System, is not big enough to be considered a true planet and should instead be called a minor planet.

Lars Lindberg Christensen of the Hubble European Space Agency Information Centre Garching, Germany, said the discovery added weight to this argument.

"People who believe that Pluto is just a minor planet will have more proof now," he told BBC News Online.

'No danger'

The icy rock is very distant from the Earth. Mr Christensen said there was no "apparent danger" that it could ever collide with our planet.

"This asteroid is one of the ones we should be least afraid of," he said.

Kuiper Belt Objects

Icy planetary bodies that orbit beyond Neptune in the distant region of the Solar System

More than 400 such objects are currently known

They are believed to be remnants of the formation of the Solar System and among the most primitive objects available for study

The observations were carried out at the European Southern Observatory with the world's first operational "virtual telescope", Astrovirtel.

"The concept of a virtual telescope is a highly sophisticated science tool that mines all of the databases to find answers to questions," said Mr Christensen.

The technology allows astronomers to combine data from conventional telescopes with a powerful search tool.

The asteroid has been designated 2001 KX76 for the time being but will eventually get a real name.

As a Kuiper Belt Object, it must be given a mythological name associated with creation.