GOOD news, Earthlings. There are fewer large, near-Earth asteroids 鈥� which could potentially crash into Earth 鈥� than previously thought.
The news comes from an infrared sky survey by NASA鈥檚 WISE satellite. Rather than relying on reflected sunlight to detect space rocks, as visible-light surveys do, WISE picked up the heat they emit. The technique is more sensitive because it depends less on the rocks鈥� colour.
鈥淎n infrared sky survey suggests there are fewer large, near-Earth asteroids than previously thought鈥�
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of NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California, and colleagues used the new census to estimate that there are 19,500 near-Earth asteroids between 100 and 1000 metres across, about half as many as previously thought.
The researchers also report that more than 90 per cent of the 981 鈥減lanet buster鈥� asteroids 鈥� those larger than 1 kilometre across 鈥� have been identified. This meets a target set by the US Congress in 1998 ().