An asteroid becomes a meteorite when it travels to Earth from a nearby orbit or the outer solar system and collides with Earth, according to the United States Geological Survey. Small asteroids typically burn up in the upper atmosphere before ever reaching Earth’s surface to become meteorites.

The chances that a space rock could hit Earth in less than a decade just went up slightly, according to NASA scientists. The asteroid 2024 YR4, which is expected to pass Earth in 2032, was recently calculated to have a 1-out-of-43 chance of striking our planet. By contrast, last week 2024 YR4 had only a 1-out-of-83 chance of striking our planet.