Friday, February 8, 2013

Asteroid to narrowly miss Earth next week

NASA says the asteroid will be around 27,700 kilometres above Earth's surface when it speeds by.

An asteroid will zoom past Earth next week in what NASA says will be the closest flyby ever predicted for an object of its size.

The 2012 DA 14, discovered by chance by astronomers after passing near Earth last February, will be around 27,700 kilometres above the planet's surface when it speeds by.

That is outside the Earth's atmosphere, but closer than the orbit of most weather and communications satellites.

Despite the close shave, NASA says there is nothing to fear.

"This asteroid's orbit is so well known that we can say with confidence that even considering its orbital uncertainties, it can pass no closer than 17,200 miles (27,700 kilometres) from the Earth's surface. So no Earth impact is possible," Donald Yeomans of NASA's Jet Propulsion Laboratory said.
"At the same time, it will pass 5,000 miles inside the ring [of satellites]".

He said the asteroid's path puts it right in the "sweet spot" to avoid having any damaging impact.
The asteroid is predicted to come closest to Earth on February 15, around 9:24am (AEDT) plus or minus a minute or two, and will pass over the Indian Ocean off Sumatra.

It will be visible with a little help from a telescope in eastern Europe, Australia and Asia, astronomers said.

'Like a star'

"What you would see through a small telescope would be something like a star, a small point of light... that moved against a background of stars," said Tim Spahr, of the Harvard-Smithsonian's Minor Planet Centre.

The asteroid measures about 45 metres in diameter. That makes it relatively small by celestial standards.

Nevertheless, if it were to hit the Earth, the impact would be roughly equivalent to a 2.4 megaton bomb - enough to flatten a large area but not globally catastrophic, Mr Yeomans said.

"The object that ... took out the dinosaurs was about 10 kilometres," he explained.

NASA estimates a smallish asteroid like 2012 DA 14 flies close to the Earth every 40 years on average, but only hits the Earth once every 1,200 years.

Statistically-speaking, that means we're probably safe for quite a while, since a similar asteroid hit just over 100 years ago.

"With an estimated size of the order of 50 metres, (2012 DA 14) is comparable in dimensions to the object that destroyed over 2,000 square kilometres of forest in Tunguska, Siberia, on June 30 1908," Mark Bailey, director of the Armagh Observatory in Northern Ireland, told AFP.

Astronomers have detected some 9,500 celestial bodies of various sizes that pass near Earth, but they estimate that is only a tenth of what is out there.


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