The moon

(CNN) -- Is it a comet? An asteroid? A spent rocket stage? Nope. That chunk of rock circling the sun close to the Earth is probably a chip off the moon, astronomers say.

The object, about 165 feet (50 meters) across, was discovered February 10 by an automated asteroid-hunting Linear telescope in New Mexico, New Scientist magazine reported Wednesday.

After six nights of observations, Gareth Williams of the U.S Harvard-Smithsonian Center for Astrophysics calculated that it circles the sun every 1.09 years at distance just 9 million km (6 million miles) beyond Earth's orbit.

Astronomers said such a path is extremely unusual, as comets and asteroids that cross the Earth's orbit normally have eccentric orbits, the magazine said.

Astronomers said that the new object, between 30 and 50 meters across, is too big to be the final stage of a rocket.

"The most likely explanation is that it's a chip off the Moon," Brian Marsden of the Harvard-Smithsonian Center was quoted as saying.

Astronomers hope perform an analysis of the mysterious object's composition that could cast light on its origins

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