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Lundi, 07 Novembre 2011 16:46

Big Asteroid to Pierce Earth-Moon Orbit Tuesday

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Big Asteroid to Pierce Earth-Moon Orbit Tuesday

By Mark Brown, Wired UK

An asteroid the size of an aircraft carrier is to soar past the Earth this week and, while NASA is certain that the space rock will not hit us, it will be our closest encounter with such a large chunk of rock in three decades.

The 400-yard-wide asteroid is called 2005 YU55 and at the point of closest approach it will graze our planet at 201,700 miles — about ten percent closer to Earth than the Moon’s typical orbit.

It is the “closest approach by an asteroid, that large, that we’ve known about in advance,” said principal investigate Lance Benner, from NASA’s Jet Propulsion Laboratory. This gives the space agency an unprecedented view of such a rare flyby — and it will take full advantage.

The North American space administration will track 2005 YU55 from the Deep Space Network at Goldstone California, and provide radar observations from the Arecibo Planetary Radar Facility in Puerto Rico. This should reveal a wealth of detail about the asteroid’s surface features, shape, and dimensions.

The Arecibo radar telescope spotted the asteroid back in April 2010, and those observations provided the ghostly image of YU55, above. NASA hopes to get higher resolution snaps — with details as fine as two meters per pixel — this month.

But what about amateur astronomers, will they be able to see it? “Absolutely,” says NASA astronomer Marina Brozovic, and a co-investigator of YU55. “8 November is when it becomes a night time object and that is when you can see it”

“400 meters, I’d say, is a moderate size asteroid, but it’s still small and very far away. You’ll need at least a six inch telescope in order to be able to observe it. You’ll see it buzzing really fast along the sky,” says Brozovic.

“The pass’s track is especially favorable for western Europe and North America. But you’ll need to know exactly where and when to look,” writes Kelly Beatty, senior contributing editor of Sky and Telescope magazine.

The when is 23:28 UK time on 8 November. As for the where, Beatty writes that, “the object will traverse the 70 degrees of sky eastward from Aquila to central Pegasus in just ten hours, clipping along at seven arcseconds per second.” A star chart is available here.

2005 YU55 is trapped in an orbit that frequently brings it back to Earth and our nearby neighboring planets — but the 2011 encounter with Earth is the closest this space rock has come for at least the last 200 years. NASA is certain that it will miss us, and “the gravitational influence of the asteroid will have no detectable effect on anything here on Earth, including our planet’s tides or tectonic plates”.

Plus, “we have a very good idea about its orbit for the following hundred years and there is no chance of impact,” says Brozovic. “We believe with these upcoming measurements at Arecibo and Goldstone we will remove this threat even further — probably for many centuries.”

Image: NASA/Cornell/Arecibo/JPL-Caltech


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