LONDON, July 3: An asteroid up to half a mile wide passed Earth at around the same distance as the Moon - a near-miss in astronomical terms. Scientists tracking the path of asteroid 2004 XP14, which is travelling at 17km per second, said they were confident there was no danger of it hitting the planet in the foreseeable future.

There had been initial concerns that the asteroid could collide with Earth later this century, but further analysis of its orbit ruled that possibility out.

It made its closest approach at around 0425 GMT on Monday when it was around 268,624 miles away - 1.1 times the Moon’s average distance from Earth. It was not possible to see it with the naked eye, but it could have been viewed by experienced observers with moderate-sized telescopes.

XP14, along with 782 known other asteroids, has been classified as potentially hazardous. If any of them were to hit Earth, the effects would be devastating. “It would probably be big enough to wipe out a small country,” Dr David Asher, of the Armagh Observatory in Northern Ireland, said.

“At least we knew about this asteroid. We should be more worried about the unknown ones. There are quite a lot of them flying around out there that are still to be discovered.”

The asteroid, discovered in December 2004, is one of a class of “Apollo” asteroids whose orbits cross that of Earth.

Although its size is not precisely known, it is thought to range between 1,345ft and 3,018ft - between a quarter and just over half a mile wide. Scientists hope to gather valuable information about XP14 by bouncing radar signals off it from the 230ft diameter Goldstone dish in the Mojave desert, California.

“Pinging” the rock with radar will allow astronomers to plot future orbits much more accurately, and may help them determine its shape. “Usually, an asteroid is just a dot seen through a telescope,” Dr Asher said.

Another asteroid due to make an even closer visit on April 13, 2029, will be easy to see with the naked eye. Asteroid 99942 Apophis, which measures around 1,000 feet across, will be visible from Asia and North Africa as it passes within 20,000 miles of Earth.—Dawn/The Guardian News Service