The asteroid, Dimorphos, is the size of a stadium — or the Great Pyramid of Giza, as one scientist put it Monday — and is about 7 million miles from Earth at the moment. It orbits a larger asteroid named Didymos. Neither poses a threat to our planet now or anytime in the foreseeable future.
This was just a test, NASA’s first demonstration of a potential planetary defense technique, called a kinetic impactor. The idea is to give a hypothetically dangerous asteroid just enough of a blow to alter its orbital trajectory…
Even small effects on an asteroid’s movement could prove a planet-saver. A collision with an asteroid, if done early enough — say, 5 to 10 years in advance of its projected encounter with Earth — could be just enough to slow it down and make it miss.