Meteors are small solid bodies, known as meteoroids, that enter a planet's atmosphere from outer
space and are raised to incandescence by the friction resulting from their rapid motion. Brilliant meteors, known as fireballs, occur singly and generally consist of a luminous head, followed by a comet-like train of
light that may persist for several minutes; some, called bolides, have been seen to explode with a sound like thunder. Fainter meteors, called shooting or falling stars, usually occur singly and sporadically. At
intervals, however, hundreds of such meteors occur simultaneously and appear to emanate from a fixed point. These swarms are called meteor showers and are named after the constellation in which they seem to have their
point of origin. Some appear annually on the same days of each year and are called periodic showers; others occur infrequently at varying intervals. The periods of meteor showers generally coincide with those of certain
comets. Most meteors are dissipated in flight and fall to Earth
as dust; a meteor that reaches the surface of the earth or another planet is called a meteorite. |
