In the vast expanse of space, an estimated 1 million near-Earth objects (NEOs), also known as near-Earth asteroids, are constantly orbiting close to our planet. Every night, astronomers track NEOs and discover new ones, noting how fast they’re traveling, how large they are and where they’re headed. Because of their work, world leaders could get advance warning if one of these celestial objects is on a collision course with Earth, helping them prepare for calamity.