Laurel, MarylandNearly seven million miles from Earth, a spacecraft traveling more than 14,000 miles an hour smashed into a small, unsuspecting asteroid that had been floating through space undisturbed for eons.
The collision between NASA’s Double Asteroid Redirection Test (DART) spacecraft and a 500-foot-wide rock called Dimorphos, which took place at 7:14 p.m. ET, marks the first time humans have intentionally changed the course of a celestial object. It's also the first test of a bold strategy that could be used to deflect any future asteroids that are on a collision course with Earth.
While scientists are confident that a large enough asteroid to cause planet-wide extinction will not threaten Earth for at least a hundred years—after which time it is difficult to predict their orbits—it is still possible that we could be surprised by a smaller, potentially city-destroying rock from space. And eventually, whether in hundreds or thousands or millions of years, it is all but certain that life on Earth will face an existential threat from an asteroid.