p l a in e t s

the relatively large natural bodies that revolve in orbits around the sun, and presumably around other stars as well, are called planets. the term does not include such smaller bodies as comets, meteors, and asteroids, many of which are little more than pieces of ice or rock. see also comet meteor and meteorite asteroid.
the sun, the nine planets, their satellites, and all the smaller bodies, particles, and dust that circle the sun form the solar system. the sun, near the center of the solar system, governs the planets orbital motions by gravitational attraction and provides the planets with light and heat. in order of increasing mean distance from the sun, the nine planets of the solar system are mercury, venus, earth, mars, jupiter, saturn, uranus, neptune, and pluto. see also gravitation solar system sun.
mercury, venus, mars, jupiter, and saturn can be seen without a telescope. the ancient greeks called them planetes, or wandere...