The Greeks and the Romans gave the names of their Gods and Goddesses and heroes to the constellations, or groups of stars, and the planets; and they believed that certain planets were lucky and others unlucky. For example, if a man was born under Saturn, he would be gloomy and unlucky (hence the English word “saturnine”); if under Mercury he would be vivacious and fickle (hence “mercurial”); if under Mars, the red planet of the god of war, he would be “martial,” or war-like; and so on. We moderns no longer believe in astrology.
We study the stars by scientific methods, and with the scientific object of finding out the truth about them. The scientific study of the stars is called astronomy to distinguish from the false science of astrology. Modern astronomers, by means of wonderful scientific instruments such as powerful telescopes, the spectroscope, etc., and with the help of mathematics, have discovered what the stars are, their size, weight, composition, their real and apparent movements, and their distances in space. Up to the time of Copernicus, an Italian astronomer in the 15th century, people believed that the earth was the centre of the universe, and that the sun, the moon and the stars revolved round it. We now know that the earth is only a small planet revolving with other planets round the sun, and that the moon is its very small satellite or servant; that the sun is only a small star; that the stars are great suns, many much larger than our sun, but at such an awful distance from us that they look like twinkling point of light. Light travels at the rate of 186,000 miles a second; and some stars are hundreds, and even thousands, of light-years from our earth. For example, a bright star called Sirius is two hundred light-years away; that is, it takes light, travelling at the unthinkable speed, 200 years to reach our eyes.
These great suns are, like ours, probably enormous masses of flaming gas; and each of them may be the centre of a universe, with planets revolving round it. The very idea of these huge suns moving in order through space, and of the awful distance between them, fills the mind with reverence and awe.