A meteor is a particle from outer space that enters Earth’s atmosphere, but does not land on Earth. Instead, the particle burns up in the atmosphere, leaving a shortlived, glowing trail that traces part of its path through the sky. Like meteorites, meteors can be as small as a grain of sand and often burn up before reaching the ground; a meteor larger than about the size of a baseball can reach Earth; in that case, we call it a meteorite.