Page:The Music of the Spheres.djvu/21



dome of the heavens with its constellations of stars turns westward at the rate of about 15 degrees an hour.

Thus the stars, in unchanging order, rise majestically above the horizon in the east, wend their way across the great expanse of sky above our heads, and disappear below the horizon in the west. It is only necessary to note the position of a particularly bright star or a conspicuous constellation lying near the horizon and then return after several hours have elapsed and again note its position in the sky to prove this general movement toward the west. This is an interesting experiment for it is often a surprise to people to hear that the stars of the heaven are constantly shifting their position throughout the hours.

Each star has an individual pathway which describes an arc across the heavens, the exception to this being the circum polar stars which describe complete circles around a point north of the zenith.

The center indicated by the curved pathways of the stars is called the Pole of the Heavens, and in the northern hemisphere this important location is marked by the North Star. The North Star, also called Polaris or the Pole Star, lies almost directly above