LOS ANGELES ? NASA says it has found more than 90 percent of the biggest asteroids that might pose a threat to Earth.
These are asteroids that are 3,300 feet wide or larger. The space agency said Thursday its sky-mapping spacecraft called WISE has discovered 911 of the 981 largest asteroids predicted by models.
Scientists say they now think there are fewer medium-sized asteroids than originally thought. They now estimate there are about 19,500 asteroids between 330 feet and 3,300 feet wide, down from 35,000.
WISE was launched in 2009 to map the whole sky in search of hidden asteroids, comets and other celestial objects. The mission is managed by the NASA Jet Propulsion Laboratory in California.
The WISE project has also been trying to figure out which asteroid cluster might have been responsible for the extinction of the dinosaurs.
In a press release, NASA stated: "While scientists are confident a large asteroid crashed into Earth approximately 65 million years ago, leading to the extinction of dinosaurs and some other life forms on our planet, they do not know exactly where the asteroid came from or how it made its way to Earth. A 2007 study using visible-light data from ground-based telescopes first suggested the remnant of a huge asteroid, known as Baptistina, as a possible suspect."
Further studies, however, cast doubt that Bapstistina was the dinosaur killer.
Source: http://feeds.cbsnews.com/~r/CBSNewsMain/~3/oc3UqEZxDJE/main20113479.shtml
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