Los Angeles: NASA says it has found more than 90 per cent of the biggest asteroids that might pose a threat to Earth.
These are asteroids that are 3,300 feet (1,005 metres) wide or larger. The space agency said today 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
(100 metres) and 3,300 feet (100 metres) 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.