There are hundreds, if not thousands, of NEOs—near-Earth objects, which are asteroids with orbits that cross Earth’s orbit. An NEO could indeed strike our planet, possibly unleashing cosmic destruction. As of early 2009, astronomers have tracked nearly 6,000 near-Earth objects. Of these, 765 have diameters of more than a mile across, and over 1,000 are considered Potentially Hazardous Asteroids (PHAs), meaning that their orbits take them uncomfortably close to Earth.