JUPITER
Last Planet   Next Planet		Jupiter, the fifth planet is by far the most massive planet. Its mass represents more than two-thirds of the total mass of all the planets, or 318 times the mass of the Earth. If Jupiter had been several times more massive, it would have been a star, because the pressure and temperature at its center would have been great enough to set off nuclear fusion. Jupiter orbits the Sun in 11.9 years at a distance of 778.3 million km, or 5.2 times the Earth's distance from the Sun. Jupiter takes its name from the supreme deity in Roman mythology, Jupiter, or Jove. He was the sky god, lightning, and rain. He was identified with the greek god Zeus. The adjective "jovial " derives from Jove, although Jupiter was only jolly half the time. "By Jove!" is a common expression seen from literature.

Source: Grollier's Multimedia Encyclopedia, © 1998 Grolier Interactive Inc.