Jupiter’s shape is greatly flattened at the poles. He spins rapidly on his axis, once in nearly ten hours, and has therefore a five hours’ day and a five hours’ night. As the slope of his axis is exceedingly slight, he can boast little or no changes of season. The climate near the poles has never much of the sun’s heat. In fact, all the year round the sun must shine upon Jupiter much as he shines on the earth at the equinoxes. But the amount of light and heat received by Jupiter from the sun is only about one twenty-fifth part of that which we receive on earth; and the sun, as seen from Jupiter, can have but a small, round surface, not even one-quarter the diameter of the sun we see in the sky. When looked at with magnifying power, the bright, starlike Jupiter grows into a broad, softly-shining disk or plate, with flattened top and bottom, and five tiny, bright moons close at hand. Sometimes one moon is on one side, and four are on the other; sometimes two are one side and three on the other; sometimes one or more are either hidden behind Jupiter or passing in front of him. Jupiter has also curious markings on his surface, visible through a telescope. These markings often undergo changes; for Jupiter is no chill, fixed, dead world, such as the moon seems to be. [Illustration: GENERAL ASPECT OF JUPITER--SATELLITE AND ITS SHADOW.] There are dark belts and bright belts, usually running in a line with the equator, from east to west. Across the regions of the equator lies commonly a band of pearly white, with a dark band on either side of “coppery, ruddy, or even purplish” hue. Light and dark belts follow one after another, up to the north pole and down to the south pole. When we talk of “north and south poles” in the other planets, we merely mean those poles which point towards those portions of the starry heavens which we have chosen to call “northern” and “southern.” You know that all the chief planets travel round the sun in very nearly the same _plane_ or flat surface that we do ourselves. That plane is called the “plane of the ecliptic.” Suppose that you had an enormous sheet of cardboard, and that in the middle of this cardboard the sun were fixed, half his body being above and half below. At a little distance, fixed in like manner in the card, would be the small body of the earth, half above and half below, her axis being in a slanting position. The piece of cardboard represents what is called in the heavens the _plane of the ecliptic_--an imaginary flat surface, cutting exactly through the middle of the sun and of the earth.