By Matt Smith, CNN <\/p>\n
updated 8:29 PM EDT, Wed May 16, 2012 <\/p>\n
This image, taken by NASA's Near Earth Asteroid Rendezvous mission in 2000, shows a close-up view of the asteroid Eros. <\/p>\n
STORY HIGHLIGHTS <\/p>\n
(CNN) -- About 4,700 asteroids are close enough and big enough to pose a risk to Earth, NASA estimated Wednesday after studying data beamed back from an orbiting telescope. <\/p>\n
The figure -- give or take 1,500 -- is how many space rocks bigger than 100 meters (330 feet) across are believed to come within 5 million miles (8 million km) of Earth, or about 20 times farther away than the moon. <\/p>\n
\"It's not something that people should panic about,\" said Amy Mainzer, an astronomer at NASA's Jet Propulsion Laboratory in California. \"However, we are paying attention to the issue.\" <\/p>\n
NASA defines a potentially hazardous asteroid as one large enough to survive the intense heat generated by entry into the atmosphere and cause damage on a regional scale or worse. The figure released Wednesday is lower than a previous rough estimate had projected, but more are now thought to be in orbits inclined like Earth's, making them more likely to cross its path. <\/p>\n
Read more space and science news at CNN.com's Light Years blog <\/p>\n
Mainzer said asteroids in orbits pitched at a similar angle offer not only a hazard, but also an opportunity. They would be easier for spacecraft to reach. <\/p>\n<\/p>\n
Follow this link:<\/p>\n
NASA estimates 4,700 'potentially hazardous' asteroids<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" By Matt Smith, CNN updated 8:29 PM EDT, Wed May 16, 2012 This image, taken by NASA's Near Earth Asteroid Rendezvous mission in 2000, shows a close-up view of the asteroid Eros. STORY HIGHLIGHTS (CNN) -- About 4,700 asteroids are close enough and big enough to pose a risk to Earth, NASA estimated Wednesday after studying data beamed back from an orbiting telescope. The figure -- give or take 1,500 -- is how many space rocks bigger than 100 meters (330 feet) across are believed to come within 5 million miles (8 million km) of Earth, or about 20 times farther away than the moon. Continue reading