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April Fools’ fly-by: Four asteroids flash past Earth in one day
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| Image from nasa.gov |
April Fools’ fly-by: Four asteroids flash past Earth in one day
Get short URL Published time: April 01, 2013 00:57
Earth is experiencing an unusual cosmic bombardment as four large
asteroids pass it in just one day. Fortunately astronomers don’t seem to
joking when saying none are expected to pose danger.
The largest is 4034 Vishnu, which is 800 meters across – the length of
the Burj Khalifa in Dubai – though much greater in mass. In comparison,
the Tunguska meteorite that devastated hundreds of miles of Siberian
wilderness when it landed in 1908 was estimated to be no bigger than 100
meters. The asteroid that may have led to the extinction of dinosaurs
65 million years ago may have been up to 10 kilometers across.
But 4034 Vushnu – which was discovered in 1986 – will pass nearly 23
million kilometers from the Earth’s surface. The closest of the four, EN
89, will be just over 5 million kilometers away from the planet. The
asteroid was only discovered a fortnight ago.
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| Orbit Diagram. Image from nasa.gov |
Although in everyday terms, the asteroids, ancient cosmic bodies that
did not form into planets, will be a distance away, they are still
classed as Close Approaches by astronomers. In total several hundred of
them happen each year, but it is unusual for so many passes to happen
over the course of one day.
The closest large asteroid to pass Earth this year was the 50-meter
DA14, which flew 27,600 kilometers from the surface in February.
Remarkably on the same day, an asteroid of up to 20-meters penetrated
the atmosphere and exploded over Chelyabinsk in Siberia.
On average, asteroids of that size enter the atmosphere every 10 years.
Those such as the Yucatan meteor that may have ended the Mesozoic Era,
are expected to impact the Earth once every 20 million years.
While, the paths of many asteroids can be charted centuries ahead (and
could even be destroyed if they head for the Earth) many, like the
Chelyabinsk Meteor, are not detected until they enter the atmosphere –
rendering the planet potentially vulnerable to impacts millions of times
more powerful than the worst nuclear explosions.
But, some are taking a more positive attitude to asteroids. Earlier this
year, Astrorank, a company that evaluates the make-up of asteroids in
view of future space mining operations, said that 4034 Vishnu – which is
composed largely of platinum and nickel-iron – is worth around $40
trillion dollars, more than half of the world’s gross national product
last year.
Posted by
Obi-Wan Kabuki
at
1:46 AM
Thanks to: http://www.americankabuki.blogspot.co.uk
