Can an asteroid hit Earth?
It is possible that an asteroid may hit Earth, but the chances of this happening are very small. Small objects - meteors and debris from comets - hit the Earth relatively often, but they are typically small objects and burn up before impacting the surface. For more information, see NASA's meteors and meteorites webpage.
Near-Earth objects (NEOs) are asteroids and comets that orbit the Sun like the planets, but their orbits can bring them into Earth’s neighborhood - within 30 million miles of Earth’s orbit. NASA and the University of Arizona are developing the NEO Surveyor mission - a planetary defense mission designed to respond to the objectives of NASA’s Planetary Defense Coordination Office by detecting, cataloguing, and characterizing NEOs larger than 140 meters. In doing so, the NEO Surveyor mission provides critical decision support to NASA and other decision-makers who must assess the risks of NEO impacts to Earth and must identify potential mitigation strategies. For more information, visit the NEO Surveyor website.
In 2018, NASA/JPL-Caltech released a map of all known Near-Earth Objects. For more information, see the map on this webpage. NASA/JPL's Center for Near-Earth Oject Studies (CNEOS) also maintains a comprehensive and current set of information about all known NEOs. See the CNEOS website for more information.