It measures 130 to 300 feet across, a pebble compared to the asteroid that killed the dinosaurs, which is estimated to have been six to nine miles in length. On the other hand, on Feb. 15, 2013, an object that measured just 65 feet across exploded in the skies over Chelyabinsk,

CAPE CANAVERAL, Fla. (AP) — The threat of a newly discovered asteroid has risen slightly in the past few weeks, as the world’s telescopes rush to track its course. But the chance of an impact is still quite slim.