Astronomers and amateurs brace for a year of comets and close asteroids
The close passing of two asteroids and two comets to be gifts from heaven for stargazers
Agence France-Presse in Paris
Astronomers are gearing for thrills this year when earth gets buzzed by two rogue asteroids and two comets.
This week, scientists who scour the heavens for dangerous space rocks will be tracking an asteroid called 99942 Apophis.
Named after an Egyptian god of evil and darkness, Apophis is about 270 metres across, a mass able to deliver more energy than 25,000 Hiroshima bombs if it ever smashed into earth.
Apophis sparked some heart-stopping moments when it was first detected in 2004.
Early calculations suggested a 2.7-per cent probability of a collision in 2029, the highest ever seen for an asteroid, but the risk was lowered after more observations.
Even so, for April 13, 2036, "there is still a tiny chance of an impact," says Nasa's Jet Propulsion Laboratory, which puts the risk at about one in 250,000.
Seeking clues, Nasa's deep-space radars at Goldstone, in California's Mojave desert, and at Arecibo in Puerto Rico will be scanning Apophis, which on January 9 will pass within 14.5 million kilometres.
"It's possible that the new measurements improve the orbit to the point that we can completely rule out an impact," JPL's Lance Benner said
On February 15, a 57-metre asteroid, 2012 DA14, will skim the planet at just 34,500 kilometres. In other words, it will spookily fly by within the orbit of geostationary satellites.
"It will be the closest predicted flyby of an asteroid," said Mark Bailey, director of Northern Ireland's Armagh Observatory.
Comets - seen by the superstitious as harbingers of great events - could make 2013 a memorable year, astronomers hope.
First up is Comet 2011 L4 (PanSTARRS), expected to be its brightest from March 8-12,US specialist Gary Kronk said.
The biggest excitement is being reserved for Comet ISON, named after the International Scientific Optical Network, which could become visible to the naked eye by late November.