JUPITER

Jupiter is the largest of all the planets, having a diameter of about 88,000 miles; it is only about 1,000 times smaller than the sun—that is, about 1,000 times larger than our earth. In volume, it is 1,300 times larger than our globe. Gravitation must be enormous on its surface. Its density is however relatively low—being only about one-quarter that of the earth. It is thought to be a world of water and more or less dense gas. It is constantly covered by a thick blanket of clouds and vapors, making direct observation very difficult—as we saw was the case with some other planets. Immense as this planet is in size, it revolves at a tremendous speed—approximately 10 hours. Owing to its immense bulk, it cools more slowly than a body such as our earth. Consequently it will take tens of millions of years for it to cool sufficiently to permit life to become manifest upon its surface. Yet it may at that time! In a sense, Jupiter may be said to be a planet of the future; when our earth is cold and dead, Jupiter may be teeming with animate existence.

Jupiter has 8 satellites, and a number of dark bands cross its surface from east to west. A certain dark spot upon its surface has caused great interest among astronomers, who are unable to determine its exact nature. This planet revolves round the Sun in rather more than 11¾ years, at a mean distance of 483,000,000 miles.