Close encounters of the Rocky Kind
July 4th 2009 07:08
Category: No Category
Image of an asteroid called 2009 HC82 marked by the arrow
This year has been a busy one for travelling asteroids culminating in close encounter back in March this year.
A Near Earth Object (NEO) named 2009 DD45 paid us a very close visit scooting by our planet at 70,000 kilometers per hour, just 40,000 miles form the earth’s surface. The object was seen over Australia after passing over the Pacific ocean.
To show some perceptive on just how close this particular asteroid was when we consider that 70,000 kilometers is just one fifth of the distance from the Earth to the moon, and only twice the distance at which geostationary telecommunications satellites orbit our earth, in astronomical terms that pretty close.
The space rock was discovered only a few days prior by Rob McNaught at Siding Spring Observatory in Australia, when it was a dim speck about 1.5 million kilometers away. It became brightest when it passed closest to Earth.
Its closest approach 2009 DD45 was over the Pacific Ocean near Tahiti, which means it could be observed from Australia, Japan, and China, but not from North America or Europe.
According to NASA's NEO program 2009 DD45 is a big chunk of rock, in the somewhere between 21 and 47 meters in diameter.
The recent discovery of a 2- to 3-km wide asteroid called 2009 HC82 has sent observers in reverse a retrograde spin to be the point.
This particular near-Earth asteroid (NEO) should have already been spotted as it has such an unusually bizarre orbit.
It is highly inclined, making it orbit the Sun backwards (when compared with the rest of the Solar System's planetary bodies) every 3.39 years. More disturbingly, it ventures uncomfortably close (3.5 million km) to the Earth, making this NEO a potentially deadly lump of rock.
2009 HC82 was discovered on April 29th by the highly successful Sky Survey, and after independent observations by five different groups, confirmed that the asteroid has an orbit of 3.39 years and that its orbit is very inclined.
So inclined in fact that the asteroid's orbit takes it well out of the Solar System ecliptic at an angle of 155°. Inclined orbits are not that rare in themselves, but if you discover an asteroid with an inclination of more than 90°, you are seeing a very rare type of object a retrograde asteroid making it more likely to make another encounter with earth with perhaps more sinister intentions.
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Astroearth
Yet despite the enormity of space we are still vulnerable to cosmic visitors.
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