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Why the Asteroid Approaching Earth Was Only Spotted 5 Days Ago

By Elizabeth Howell

Why the Asteroid Approaching Earth Was Only Spotted 5 Days AgoAsteroid 2018 CB will pass closely by Earth on Friday, Feb. 9, at a distance of about 39,000 miles. Credit: NASA/JPL-Caltech

Almost exactly five years ago, a truck-size celestial rockunexpectedly exploded in the atmosphere above Chelyabinsk, Russia, on Feb. 15, 2013. As town officials dealt with broken glass and hundreds injured, people worldwide asked why nobody spotted the 51-foot-across (17 meters) object sooner, in time to warn residents.

The same question could be asked of another asteroid that will whiz harmlessly past the Earth today (Feb. 9). NASA said this object, nicknamed 2018 CB, may very well be bigger than one that broke up over Chelyabinsk. The asteroid was only spotted on Sunday (Feb. 4) by the Catalina Sky Survey. Early estimates of 2018 CB’s size range between 50 and 130 feet (15 and 40 m) in diameter. The object will fly by Earth at about 5:30 p.m. EST (2:30 p.m. PST) at less than 20 percent of the distance from the Earth to the moon. That’s about 238,855 miles (384,400 km) from us.

“Asteroids of this size do not often approach this close to our planet — maybe only once or twice a year,” Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in California, said in a statement from the agency.

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