Museum curators are left feeling like it is the end of the world after a brazen thief walked away with a rare model of the Earth.

The 300-year-old globe had been on show in the basement of the Museum of the History of Science, Broad Street, Oxford, for the past 80 years.

But a thief stole the £4,000 antique by walking in to the museum during opening hours and removing it from its mounting, possibly making off with it in their pocket.

The globe was part of an 18th century Orrery, a model of the solar system demonstrating how the planets rotate around the Sun.

It was stolen on Thursday, 11/05but police only released an appeal for information yesterday. Distressed museum staff are hoping the globe, designed and made by Richard Cushee in 1731, will be returned.

Police think the rare exhibit may have been stolen to order to be sold to an art collector on the black market.

Museum director Dr Jim Bennett said: "I don't honestly know if it's been stolen for order or by an opportunist thief. If it's a prank they might throw it away, but if they know the value of it they might return it.

"We feel responsible for this - it's been sitting there for 80 years."

The globe is roughly 7cm in diameter, has a printed map of the Earth mounted on the sphere and was connected by brass rods to the rest of the Orrery. A lever is used to move the planets.

The Orrery only shows the Earth, five other planets, the Sun and the Moon because the rest of the planets in the solar system had not been discovered when the piece was made.

An unspecified reward has now been offered by Crimestoppers for the globe's safe return.

Police are now looking at CCTV footage. Pc Steve Mather said: "There is a possibility it has been stolen by someone who knows its worth and wants to sell it on.

"I hope people working in the antiques trade will help us if they come across it or if it is offered for sale."

Anyone with information should ring Pc Steve Mather on 0845 8505505 or anonymously call Crimestoppers on 0800 555111.