An asteroid up to 600 metres in length rushed past Earth yesterday morning, giving astronomers a rare and relatively close-up glimpse of such a large object in near space.

There are hundreds of thousands of asteroids in the solar system orbiting the sun, but the next time one will race through so close to the planet will be in 2027. Asteroid 2007 TU24 was expected to pass 334,000 miles away, about 1.4 times the distance between the Earth and the moon.

Despite the outlandish predictions of some Internet pundits, the future of humanity was never at risk yesterday. But scientists were hoping to use the fly-past to work out how best to defend the planet against asteroids in the future.

Nasa monitored it closely in an attempt to determine whether it is a solid object or simply a loose pile of space rubble.

Asteroid 2007 TU24 was only discovered on October 11 last year by the NASA-sponsored Catalina Sky Survey at Arizona University. It is of an estimated 7,000 near-Earth objects.

Visible

The asteroid should have been visible through modest-sized telescopes with apertures of at least 7.6cm (three inches), but quickly became fainter as it moved away from the Earth.

Mike Nolan, head of radar astronomy at the Puerto Rico observatory, said: "We have good images of a couple of dozen objects like this, and for about one in 10, we see something we've never seen before. We really haven't sampled the population enough to know what's out there."

Tomorrow, the 2007 WD5, another asteroid, is due to shoot within 16,250 miles of Mars. Initial calculations had suggested the object may collide with the red planet, but that has now been virtually discounted.

- Times of London