[THE UNIVERSE]—[THE SOLAR SYSTEM]—[PLANETS]—[SUN]—[MOON]—[CONSTELLATIONS]—[STARS]—[COMETS]—[METEORS]—[NEBULÆ]—[NEBULAR HYPOTHESIS]—[ECLIPSES]—[MYTHOLOGY OF THE CONSTELLATIONS]—[DICTIONARY OF SCIENTIFIC TERMS USED IN ASTRONOMY].
HOW THE PLANETS WOULD APPEAR IF GROUPED IN SPACE
In the above picture we have represented the planets of the Solar System as we should see them from the earth if the human eye could grasp a space of such immensity. The spectator is supposed to be standing on the earth, and the moon is in the foreground, 240,000 miles away. The planets are in their order outward from the sun, and vary in distance from 40,000,000 miles, in the case of Mars, to 2,700,000,000 miles in the case of Neptune. From the bottom upward, the planets are Mercury, Venus, Mars, Jupiter, Saturn and its rings, Uranus and Neptune.
THE WORLDS IN THE SKIES
The earth upon which we live is only one of many worlds that whirl through space. If we are to understand our own world, we must first learn something about the worlds in the skies. These bodies are arranged in groups, or systems, sweeping through circuits that baffle measurement; and such is the magnitude of the boundless space they occupy that our entire solar system is only a point in comparison. To this vast expanse of worlds, and systems and space we give the general name Universe.
THE SOLAR SYSTEM AND
ITS MEMBERS
First in importance to us in this immense space filled with stars is what astronomers call the Solar System, so-called because the sun is its center. It contains the planets, eight in number, of which our earth is one. They have been named after the ancient deities; the two interior ones, Mercury and Venus, and the exterior ones, Mars, Jupiter, Saturn, Uranus, and Neptune; the first three being smaller than our earth, and the remainder a great deal larger.
Mercury and Venus are known to be interior planets, that is, planets between us and the sun, because they appear to swing on either side of the sun. Mercury very seldom leaves the sun sufficiently to rise so early before the sun, or set so late after him, as to be visible. Venus, however, gets so far away as to be seen long after sunset or before sunrise, and is called the Evening or Morning star, accordingly.
Besides the planets there are other members of the system, namely, comets and falling stars, which will be mentioned again more fully hereafter. All these bodies form a sort of family, having the sun for their head. The illustrations and drawings on separate pages give a view of the entire system.