Over 40,000 near-Earth asteroids have been detected since 1990
Since the late 20th century, astronomers and space agencies have taken steps to monitor the threat of large asteroids passing near Earth. They set up international efforts to find these objects early, track their paths, and learn more about what they’re made of, so we’d have the best chance of spotting a real collision risk in time.As the chart shows, more than 40,000 near-Earth asteroids have been discovered and tracked since 1990. NASA estimates that we’ve already found over 90% of near-Earth objects larger than 1 kilometer. These are the most dangerous ones, because an impact at that size could cause global-scale damage.Explore more interactive charts on space exploration and satellites →