Near-Earth Objects: There are many objects in space that come close to earth's orbit. The velocities of asteroids or other near-earth objects (NEOs) that the National Aeronautics and Space Administration (NASA) and other in the international community are examining are about seventeen kilometers a second—the energy releases are equivalent to the detonation of a nuclear weapon. NEOs that are of concern, “potentially hazardous objects,” are ones where their orbits bring them into five million miles of Earth's orbit. NASA and other observatories around the world are constantly scanning the skies for potentially hazardous “near-Earth objects,” and thousands have already been found. At the start of 2019, the number of discovered near-Earth asteroids totaled more than 19,000. An average of thirty new discoveries are added each week. NASA estimates that at least 17,000 big near-Earth asteroids have yet to be discovered.
