WASHINGTON — This year's second-largest "potentially hazardous" near-Earth object is incoming at speeds of over 11,000 kilometers per second and will zoom past our planet on May 21.<br /><br />Asteroid 136796, also known as 1997 BQ, is estimated by NASA to be between 640 meters and 1.4 kilometers wide, or roughly the size of the Golden Gate Bridge.<br /><br />1997 BQ orbits our Sun every 844 days. According to NASA's Asteroid Watch, on May 21 it will pass Earth at a distance of 6.2 million kilometers, slightly closer than this year's largest potentially hazardous near-Earth object, 1998 OR2, which flew past Earth on April 29 at a distance of 6.3 million kilometers.<br /><br />NASA classifies a near-Earth object — either a comet or an asteroid — as a potentially hazardous object if its orbit brings it within 7.5 million kilometers of Earth's orbit and it is greater than 140 meters in size.<br /><br />According to NASA's Center for Near-Earth Object Studies, as of April 21, some 22,582 near-Earth objects had been discovered. Of these, 9,085 were 140 meters or larger in size, and 902 were estimated to be larger than one kilometer.<br /><br />By comparison, the Chicxulub asteroid that wiped out the dinosaurs is estimated to have been 11 to 81 kilometres in diameter.
