"Falling stars" are actually meteors, solid bodies that travel through space. These falling bodies become visible at night when the friction between the surfaces of the meteors and of the air produces heat as the meteors enter the earth's atmosphere. The intense heat burns up the meteors, which leave a blazing trail of light as they fall. Scientists call meteors that actually fall to the ground meteorites. However, many meteors burn up completely before hitting the earth's surface.