Amazing Facts About Jupiter
Jupiter is a planet of extremes. It is the largest planet in the solar system, both in terms of diameter and mass. It has the strongest magnetic field of all the planets in the solar system. It has the shortest day of all the planets. As a result, it rotates so fast that it appears noticeably squashed: it is 7% longer across its equator than between its poles. Most of the time, Jupiter is the third brightest object in the night sky, outshone only by the Moon and Venus. Its name comes from the mythical Roman god Jupiter, or Jove, the head of the pantheon, called in Latin "Father God the Best and Greatest."
Jupiter's famous Great Red Spot is an enormous hurricane-like storm that has persisted for at least 400 years. Large enough to swallow the Earth three times over, many aspects of the Great Red Spot remain to be explained by science.
Jupiter has 63 known natural moons, and the four largest are the most famous. Io, Europa, Ganymede, and Callisto were the first moons discovered in the solar system orbiting a planet besides Earth. They are called the Galilean moons after their discoverer, Galileo Galilei. The discovery of objects orbiting a body other than Earth was one of the observations that later led to the acceptance of the heliocentric theory of the solar system.
The moon Europa has a special claim to fame: its rocks are similar in composition to the Earth (silicate rocks on the surface and an iron core), its atmosphere contains oxygen, and it likely has an ocean of water beneath its surface. Many astrobiologists believe it is possible that extraterrestrial life exists on Europa.
Image, above right: Jupiter's Great Spot compared to Earth. This composite shows an approximate size comparison between the Earth and Jupiter and its Great Red Spot. http://commons.wikimedia.org/wiki/File:Jupiter-Earth-Spot_comparison.jpg