An irregularly-shaped space rock nearly 4 m in length and 1.5 to 2.3 m across has entered Earth's gravitational field claimed an amateur astronomer.

''The rock,named 6RIODB9, suddenly entered our planet's gravitational field on June 12 and is slowly making revolutions along the Earth. On June 17, it will be at a distance of nearly 203,000 km from our planet. A similar 'rock' was observed in September 2006 by The University of Arizona's Catalina Sky Survey,'' said Dr Ram S Shrivastava.

A group of scientists were considering that 'rock' as a spacecraft fragment of NASA's Apollo programme undertaken in the sixties.

''The present rock can be termed an asteroid of unknown nature,'' said Dr Shrivastava.

Sunlight reflecting off its surface proved that it is a solid mass of several tonnes and had there been strong solar activity at this juncture, the rock's path might have changed and it might have come more closer to Earth thereby endangering geostationary satellites.

''Most scientists are considering that the rock is nothing but a tiny part of the Moon ejected after a major asteroid impact,'' the astronomer added.