[attach id=235644 size="large"]Press Association Graphic. Source: NASA.[/attach]
An asteroid capable of destroying London will skim past Earth on Friday, approaching closer than many satellites.
Scientists say they are sure there is no chance of the 45.7-metre-wide space rock hitting the planet.
But there is a remote possibility that it could collide with one of more than 100 telecommunication and weather satellites in fixed orbits above Earth.
The asteroid, 2012 DA14, has been closely tracked since its discovery a year ago.
It is predicted to reach its nearest point to Earth at around 8.30pm Malta time on Friday.
Experts have calculated it will stay at least 27,681km away – easily far enough to be safe, but a very close shave in astronomical terms. Scientists have never observed such a narrow miss before.
Through binoculars, the object should be visible as a tiny dot of light crossing the sky
Through binoculars, the object should be visible as a tiny dot of light crossing the sky.
Astronomer and asteroid expert Dan Brown, from Nottingham Trent University, said: “It will be too faint for the naked eye but with binoculars it should be visible if you know where to look. It will be low to the northeastern horizon and moving quite quickly.
“You’ll be able to see it pass from the constellation Leo to roughly the Plough, and it will be bright for about an hour.”
DA14 belongs to a dangerous family of near-Earth objects (NEOs) that are small enough to be missed but large enough to cause serious damage. It was detected in February last year by La Sagra Observatory in southern Spain as it fell under the spotlight of the Sun’s rays.
Travelling at between 20,000kph and 30,000kph – around eight kilometres a second, or eight times the speed of a rifle bullet – the asteroid will fly inside the orbits of high geostationary satellites some 35,406km above Earth.
“These are the satellites that provide us with telecommunications and weather forecasts,” said Brown.
“There are loads of them but you’re talking about a very big area. It would be very unlucky if a satellite was hit. The asteroid is more likely to hit some space junk, but most of this is only about a centimetre across and the impact won’t even be noticed.”
The asteroid will pose no danger to the International Space Station, which orbits at an altitude of only a few hundred kilometres.
Precise calculations showed there was absolutely no possibility of DA14 hitting Earth, Brown said. But scientists had a good idea of what the effect of such an impact would be because a similar sized meteor devastated a remote region of Siberia in 1908.
Exploding a short distance above the ground over Tunguska, the object generated a blast 1,000 times more powerful than the atom bomb dropped on Hiroshima. Forest was completely flattened over an area of 2,150 square kilometres.