Astronomers look for near-Earth objects

Astronomers look for near-Earth objects
因為在經過YAHOO的時候見到, 而香港、台灣等都沒有這篇新聞tvb now,tvbnow,bttvb  Q- e6 b1 D' I& b' A0 n! J
不分享覺得蠻可惜的....

其實這個就是其中一個將有可能撞到我們地球的小行星
這個行星就是其中一顆Apophis小行星
這個小行星也就是在怪異區裡面分享過的 小行星Apophis2029年撞地球
http://www.tvbnow.com/viewthread.php?tid=8953&extra=page%3D1: p. @. ^$ n7 u* n! B
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They won't be sure until it makes an earlier pass in 2029,5.39.217.76  V4 x( o0 D3 p

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By WILLIAM J. KOLE, Associated Press Writer
Thu Aug 17, 7:47 PM ET9 s# W. Y. w9 O6 y, G
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PRAGUE, Czech Republic - They're out there, hidden among a haze of stars — killer asteroids. Now the world's astronomers are keeping a wary eye to the skies for giant objects on a collison course with Earth.
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Experts say there are about 1,100 comets and asteroids in the inner solar system that are at least a half-mile across, and that any one of them could unleash a global cataclysm capable of killing millions in a single blinding flash.

On Thursday, the International Astronomical Union said it has set up a special task force to sharpen its focus on threats from such "near-Earth objects."

"The goal is to discover these killer asteroids before they discover us," said Nick Kaiser of the University of Hawaii's Institute for Astronomy, which hopes to train four powerful digital cameras on the heavens to watch for would-be intruders.公仔箱論壇2 S6 v7 f$ Q- I6 O6 q' j+ h

There are no asteroid busters to stop one right now, but scientists believe that one day a defense could be devised, such as using spacecraft to divert a killer comet.公仔箱論壇+ _+ t* N5 m' E
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Congress has asked       NASA for a plan to comb the cosmos for even smaller, more distant objects, including asteroids just 1 1/2 football fields across. The space agency is to catalog their position, speed and course by 2020. Already, there are 103 objects on an "impact risk" watch list.公仔箱論壇3 }. G1 X" f; M+ F3 r+ y; h

Scientists warn there are as many as 100,000 of these "smaller" heavenly bodies with the potential to take out entire cities or set off a tsunami like the killer wave that swept through the Indian Ocean in December 2004.tvb now,tvbnow,bttvb; k, ?7 J3 M( B2 c
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Earth's craters bear silent witness to what can happen even when a smallish asteroid slams home. In 1908, one struck remote central Siberia, unleashing as much energy as a 15-megaton nuclear bomb. Fortunately, it wiped out 60 million trees, not people. Had it hit a populated area, the loss of life would have been staggering.

There's some recent good news too: Earth's most pressing threat — the asteroid 99942 Apophis — appears to have eased. Scientists initially gave it a 1-in-5,500 chance of hitting the planet in 2036, with enough power to wipe out the New York City metro area. But experts said Thursday the latest observations suggest those odds have dwindled to 1-in-30,000.; B5 }* ]9 e" V7 ^

They won't be sure until it makes an earlier pass in 2029, when it's expected to come within 18,640 miles of Earth. If that sounds comfortably distant, consider this: It's closer than many commercial satellites and a good deal nearer than the moon.tvb now,tvbnow,bttvb3 W+ f$ A9 |( P3 j' _$ d
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Although close encounters are unnerving, they give astronomers a unique opportunity to get a better glimpse of asteroids and comets — the leftover building materials of the universe — and gain a better understanding of the origins of the solar system.

Scientists say expanding their database of the objects crowding Earth's neighborhood could help produce a permanent warning system like those that now monitor the Pacific for tsunamis or keep tabs on volcanoes and earthquake zones.
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Give the world a decade or so of lead time to deal with a specific threat, they say, and it stands a chance of getting out of harm's way — perhaps by sending up a spacecraft to nudge an asteroid off-course.& e; a( ]% N) @/ f* E
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"Right now, unfortunately, there are no 'asteroid busters' or hot lines. Who ya gonna call?" said Andrea Milani Comparetti, a professor of mathematics at Italy's University of Pisa.tvb now,tvbnow,bttvb9 J9 b+ M) x5 Z6 d$ p) R$ Y- i5 Q

To be on the safe side, astronomers trying to determine the odds of one hitting Earth work with computer models that surround it with thousands of "virtual asteroids." Experts then map out the likely orbits for each one and factor those in to come up with the probability of an impact.TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。2 g0 f, J* `: Z; d1 e' A! r

But widening the search for threatening objects creates a problem: Discoveries could become commonplace, either creating unnecessary panic and confusion or lulling the public into a false sense of complacency.
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"We're now going to be finding such objects once a week instead of once a year," said David Morrison, a NASA scientist who will chair the new task force.
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"Only in Hollywood do asteroids arbitrarily change orbits," he said. "But there is great potential for misunderstanding. Dealing with probability and risk is a problem for all of us, whether we're dealing with asteroid impacts or terrorist attacks."
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Bottom line: Mankind may not be able to dodge every cosmic bullet. 公仔箱論壇+ F2 Q. T' H8 R' M9 m

"It's through collisions that planets are born," said Giovanni Valsecchi of Italy's National Institute of Astrophysics. "And it's through collisions that planets die."

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