Illustration showing the orbits of the binary near-Earth asteroid Didymos (labelled) and another 2,200 potentially hazardous asteroids (fainter lines) around the Sun. An asteroid is classified a potentially dangerous when it is wider than 140 metres and its orbit brings it within 8 million kilometres of Earth's orbit. Didymos is the target for NASA's Double Asteroid Redirection Test (DART) mission. The DART spacecraft will crash into the asteroid in an experiment to see if the Earth might be protected against an asteroid collision by changing an asteroid's orbit.