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Millions of observers worldwide watched Friday as two giant space rocks—one scientists had their eyes on for months and one they completely missed—narrowly avoided and smashed into Earth, respectively.

The coincidence—astronomers have determined that the Russian meteor, the largest to crash into Earth in more than 100 years, and the swimming-pool sized 2012 DA14 asteroid were unrelated—has brought a renewed focus on how NASA and its partners detect so-called “near-Earth objects.”

Paul Chodas, of NASA’s Jet Propulsion Laboratory, says NASA and its international partners detect about 95 percent of all asteroids and meteors that have any chance of impacting Earth. But smaller pieces bombard Earth every month or so and there is still work to be done to improve asteroid detection, Chodas says. NASA has found more than 9,730 near-Earth objects and says more than 800 of them have a diameter of more than half a mile. NASA estimates that there are as many as 500,000 near-Earth asteroids the size of DA14.

Friday’s events are “just a reminder that it’s a shooting gallery out there and we’re right in the middle of it,” Chodas says. “We do a good job detecting near-Earth objects, but we need to get better at detecting smaller asteroids.”

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