Asteroid to buzz the earth

Amateur stargazers will have a once-in-a-decade opportunity to see an asteroid half-a-kilometre wide "narrowly" miss the Earth on Monday, January 26.

The space rock, code-named 2004 BL86, is expected to reach a point about 1.2million kilometres from the Earth, or three times the distance to the moon.

Although easily far enough away to be safe, the flyby - at an estimated 56000km/hour - counts as a close shave in astronomical terms. It will be the closest any asteroid comes to Earth until the predicted fly-past of another rock, 1999 AN10, on August 7 2027.

Don Yeomans, the retiring head of the Nasa's near-Earth object programme, said: "Monday, January 26 will be the closest asteroid 2004 BL86 will get to Earth for at least the next 200 years.

"And while it poses no threat to Earth for the foreseeable future, it's a relatively close approach by a relatively large asteroid, so it provides us with a unique opportunity to observe and learn more."

Nasa's near-Earth object programme, also known as Spaceguard, searches for objects that might potentially pose a hazard to the planet.

The BL86 asteroid is likely to be bright enough for amateur astronomers to spot with small telescopes or good binoculars.

Nasa's Deep Space Network antennae at Goldstone, California, and the Arecibo Observatory in Puerto Rico will be used to obtain science data and radar-generated images of the asteroid.