NASA: 19,500 mid-size asteroids around Earth, fewer than expected

NASA WISE satellite surveys space to objects heading toward Earth

nasa wise asteroid count
First the good news: There are far fewer near Earth asteroids than NASA previously thought and it knows now where 90% of them are.  The bad news, if you will is that there are still 19,500 mid-sized asteroids floating around out there.

In the past NASA had estimated there were about 35,000 mid-sized, near-Earth asteroids which are defined as objects between 330 and 3,300-feet wide. Such objects could destroy a metropolitan area if they were to hit in the wrong place. NASA said there was also a small drop in the number of large near-Earth asteroids, which are 3,300 feet and larger and said that 93% of that estimated population have been found.

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"Large asteroids are about the size of a small mountain and would have global consequences if they were to strike Earth. The new data revise their total numbers from about 1,000 down to 981, of which 911 already have been found. None of them represents a threat to Earth in the next few centuries. It is believed that all near-Earth asteroids approximately 6 miles across, as big as the one thought to have wiped out the dinosaurs, have been found," NASA stated.

The new numbers come from asteroid observations released today by NASA's Wide-field Infrared Survey Explorer, or WISE satellite which looked at the objects that orbit within 120 million miles of the of the sun into Earth's orbital vicinity, NASA said. WISE scanned the entire celestial sky twice in infrared light between January 2010 and February 2011, continuously snapping pictures of everything from distant galaxies to near-Earth asteroids and comets, NASA stated.

The survey project, called NEOWISE, is the asteroid-hunting portion of the WISE mission and it observed more than 100 thousand asteroids in the main belt between Mars and Jupiter, in addition to at least 585 near Earth, NASA noted.

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NASA added that the WISE observation fulfill a congressional mandate that the space agency identify at least 90% of near Earth objects by 2020.

NASA detects and tracks asteroids and comets passing close to Earth through its Near Earth-Object Observations Program or "Spaceguard." The program has been in the news lately as NASA responded to the inordinate amount of doomsday reports that comet Elenin which will pass by Earth October 16 has generated.

"The risk of a really large asteroid impacting the Earth before we could find and warn of it has been substantially reduced," said Tim  Spahr, the director of the Minor Planet Center at the Harvard Smithsonian Center for Astrophysics in Cambridge, Mass., in a statement.  

 Follow Michael Cooney on Twitter: nwwlayer8  

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