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 range from the size of a grain of sand on up; most of the time, though, a meteor larger than about the size of a baseball will reach Earth, in which case we call it a meteorite.
Barringer crater in Arizona is clear physical evidence of the power of a meteor impact. (NASA)