THE NEW HEAVENS.
THE largest telescope yet made, having a 100-inch reflector, is installed at the observatory of the CamegieInstitution on Mount Wilson, California. With this mighty instrument the astro- nomer may hope to penetrate still farther into stellar space and learn still more of the nature of the stars. Dr. G. E. Hale, the director of the observatory, has just reprinted, under the title of The New Heavens (Scribner, Is. 6d. net), three remarkable articles from Scribner's Magazine, which describe the giant telescope and explain the problems which it is helping to solve. His photographs show better than words could do what greatly enlarged images of very remote stars can now be obtained. " The increased light-gathering power "—nearly three times as large as that of the 60-inch reflector at Mount Wilson—" will mean the addition of many millions of stars to those already known," and spectroscopic observations can be made of stars down to the fifteenth magnitude. Dr. Hale explains the prin- ciple of the Michelson interferometer, by which the diameters of stars can be accurately measured. He tells us that, with this instrument adjusted to the new telescope, Betelgeuse, the red star in Orion, has been measured and found to have a diameter far exceeding a hundred million miles. Light, travelling 186,000 miles a second, takes 160 years to reach the earth from Betelgeuse. The mind cannot realize the full meaning of such figures ; the Miltonic account of Satan
" Coasting the wall of Heaven on this side Night, In the dun air sublime " is less exact, but more expressive. The giant telescope enables man to see more of the universe, but proves also that beyond the bounds of human vision there is still space, finite according to Einstein, but without known limits— space in which a star like Betelgeuse, whose volume is at least a million times as great as that of the sun, can move freely in its course. Betelgeuse is not the largest star known : Antares has twice its diameter and is more than twice its distance from our little earth. Dr. Hale outlines the problems of stellar chemistry in a fascinating chapter. In these " cosmic crucibles " the spectroscope seems to reveal the elements in process of formation. The new electrical theory of matter has revolu- tionized the old conception of the history of a star. We are now to suppose that the life of a star must extend over many thousands of centuries, from its earliest stage as an immense mass of cool gas—such as hydrogen or helium—to its later stages as a -smaller mass radiating intense heat, like the sun, and containing many complex elements. Dr. Hale, in conclusion, reminds the " practical man " that modern inventions are based on research undertaken for purely scientific reasons. There is no knowing what may come of the study of stellar chemistry, but it is, at any rate, a profoundly interesting subject. •
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