Page:Popular Science Monthly Volume 65.djvu/9



N the fruitful field of astrophysical research there are few opportunities for advance so promising as those afforded by the study of the sun. As the central body of the solar system, maintaining the planets in their orbits by the power of its attraction, and supplying light and heat to the inhabitants of the earth through its radiation, the sun is an object of special interest to every student of nature. Its appeal to the imagination may be said to be threefold in character. In the first place, because of the extraordinary nature of the phenomena on its surface, and the stupendous scale of the eruptive disturbances, which are becoming more and more frequent in the present period of solar activity, the study of the sun for the purpose of gaining an understanding of its structure is in itself a sufficiently attractive object. To some, however, whose interests are aroused more particularly by the problems of chemistry and physics than by those of astronomy, this aspect of solar research may not possess special interest. But through the development of astrophysical methods, it is precisely to the physicist and the chemist that the sun should make a special appeal. For the solar observer may be the spectator of physical and chemical experiments on a scale far transcending any that can ever be performed in the laboratory. In this enormous crucible, heated to temperatures greatly exceeding those attainable by artificial means, immense masses of luminous vapor, including most of the elements known on the earth and many not yet discovered here, may be seen