Asteroid DA14 safely skirts Earth in record proximity
Published Friday, February 15, 2013 8:18AM EST
Last Updated Friday, February 15, 2013 10:47PM EST
The Earth survived a close call with a 143,000-tonne asteroid Friday as it whizzed by our planet at a distance closer than any other cosmic rock its size.
Asteroid 2012 DA14, as labelled by NASA, came within 27,600 kilometres, closer than some satellites orbiting the Earth.
The asteroid is only about 50 metres wide, but scientists said it could have done “immense” damage if it ever struck our planet because of its weight.
By comparison, the asteroid that struck Earth 65 million years ago and is believed to have wiped out dinosaurs was nearly 10 kilometres across.
Astronomers watched DA14 pass us by over the Indian Ocean at about 2:25 p.m. Eastern time. It was very difficult to see the rock with a naked eye, but residents of some parts of Asia, Australia and eastern Europe were able to catch a flash of light with telescopes and binoculars.
NASA said the close encounter was not related to another spectacular cosmic event on Friday – a meteor explosion above Russia’s Ural Mountains.
NASA estimates that the meteor was about 15 metres wide and weighed 7,000 tonnes before it burst into the atmosphere. The explosion injured an estimated 1,000 people, shattered windows and caused panic among the residents of Russia’s Chelyabinsk region.
Experiencing a meteor explosion and a close asteroid sighting is “very rare and historic,” said Jim Green, NASA's director of planetary science.
"These fireballs happen about once a day or so, but we just don't see them because many of them fall over the ocean or in remote areas. This one was an exception."
As for the asteroid, NASA estimates that an object of that size makes a close approach every 40 years. The likelihood of it striking the Earth is every 1,200 years.
The chances of us getting hit by a large asteroid without warning are “extremely low, so low that it’s ridiculous,” said former Apollo astronaut Rusty Schweickart, who is now the chairperson emeritus of the B612 Foundation monitoring dangerous asteroids.
“But the smaller ones are quite different," Schweickart said. "If we get hit by one of them, it's most likely we wouldn't have known anything about it before it hit."
A spacecraft could theoretically be launched in an effort to change the direction and speed of an asteroid that’s on a collision course with Earth.
But scientists would need to know up to 30 years in advance of a large asteroid’s approach to successfully deflect it, Schweickart said.
Experts say there could be anywhere between 500,000 and one million “near-Earth” asteroids in space, but less than one per cent have been spotted. Only 9,600 asteroids have been catalogued by astronomers.
NASA says the Earth’s atmosphere gets hit with 100 tonnes of “space junk” every day. Most of it is tiny and burns up before reaching the ground.
With files from The Associated Press