As marvellous as the comets, are the temporary stars. Several instances are on record where stars have suddenly appeared where no star had been seen before. They shone for a time with splendor, then faded away. In November, 1572, a magnificent new star shone in the constellation of Cassiopeia. In eighteen months it vanished. During the seventeenth century “Kepler’s Star” appeared in the constellation of The Serpent Bearer, and surpassed all the finest stars near it in brightness. It gradually lessened, and in two years was lost to view. Other wonders of the heavens are the variable stars. The light of these stars changes greatly. Week after week they brighten as the sun brightens from dawn to noon; then for an equal period they pale and fade, to revive in splendor and again to wane. There are also stars that fix our attention by being binary or double. These are twin stars situated very close together, and revolving around each other. After the binary stars were discovered, it was found that there were also multiple stars; that is, three or four stars similarly situated in relation to each other, and circling about each other. These binary and multiple stars are usually of different colors, as a green and a red, an orange and a blue, or blue, green, orange, and red in a four-fold star. Most of the stars are so very far from us that we cannot learn much about them. What we call our own solar system embraces our sun and a certain number of planets, which depend on our sun for heat and light, and constantly move about the sun in great and nearly circular paths. By means of telescopes and other instruments we are able to study our own sun and his system of dependent planets. When we examine distant stars they seem to us to be like our sun, and so we conclude that like him they may be centres of systems and have planets wheeling about them. If there were such planets we could not see them, owing to the greatness of the distances. Planets are dark in themselves, as our world is, and shine only by reflected light from their suns. These suns are the stars of the field of heaven. Suns are stationary with respect to their accompanying planets, but with respect to other systems it is probable that each system is in motion and moves about some distant centre, led by its sun along some path which no mind can calculate. As we look upon the heavens we can consider that all these glowing bodies are moving on some majestic path through infinite space. The star Alcyone, in the Pleiades, has been conjectured by Mädler of Dorpat to be the centre of gravity, or central sun of all the known universe.[16] The Pleiades, often called “The Seven Stars,” are a grape-shaped cluster, of which six stars are large and beautiful, while many smaller ones appear like a soft, golden haze.