National Geographic : 1952 Feb
Our Universe Unfolds New Wonders Multitudes of Heavenly Bodies and Clues to Creation's Riddles Are Found by the National Geographic-Palomar Sky Survey BY ALBERT G. WILSON In 1949 the National Geographic Society and the California Institute of Technology launched a four-year program at Palomar Observatory to map the heavens photographically in far greater detail than previously had been possible. With the project now near its half way mark, the astronomer in charge tells here of the great numbers of nebulae, stars, comets, and asteroids already recorded on the new sky charts, and how the Survey is opening the way to a better understanding of the structure and evolution of our universe.-The Editor. ANEW and exciting picture of our vast universe, revealing details never known before, is taking shape as the great telescopes of Palomar Observatory sweep the skies. Out in the depths of space we are finding immense numbers of celestial bodies, great and small, near by and far away, in regions of the heavens previously unexplored. At the same time we are discovering im portant new clues to the mysteries of how large the universe is and how it is put to gether, and to the intriguing question of whether it is expanding at inconceivable speed. This new "portrait of creation" is based on the photographic maps of the heavens now being produced by the National Geo graphic Society-Palomar Observatory Sky Survey on a California mountaintop.* In four years, on 1,870 photographic plates, the Survey will chart more than three-quarters of the entire sky, all that is visible from the latitude of Palomar. The photographs will be published in a Sky Atlas which will sup ply astronomers with enough material for a century of study (page 246). Exploring the Unknown Sky Though the Survey's four-year task of map ping the sky is only about half completed, the results already are giving us a new con ception of the universe around us. Now, for the first time, man can see what the universe is like for vast distances out in all parts of the sky visible from Palomar. The Survey photographs include objects whose light, traveling 186,000 miles a second, takes 300 million years to reach the earth. Earlier, astronomers had penetrated even farther out, but only in a few scattered sec tions of the sky, about one percent of the total area. The rest of the heavens had been charted only for comparatively short distances outward. The remoter parts of the universe were largely unknown territory. But now the Sky Survey is rapidly opening up these virgin regions. New discoveries on the Survey's photographs are turning up in tremendous numbers. We astronomers are as excited about these finds as geographers would have been in 1492 if Columbus had brought back aerial photographs of all of North America. Telescopes Work Together This large-scale mapping of the universe is made possible by the new wide-angle 48 inch Schmidt telescope-camera on Palomar, which can photograph a section of the sky as large as the bowl of the Big Dipper on a single picture. Each picture will record all the visible heavenly bodies out to an average distance of 2,000 billion billion miles! The "Big Schmidt" telescope is working in close partnership with Palomar's giant 200 inch Hale telescope. Because the 200-inch can photograph at one time an area of the sky only a quarter the size of the full moon, it is not suited for mapping the entire heavens. Instead, its power can be used on objects of special interest found on pictures taken by the Schmidt, photographing both their images and the spectra of their light on a larger scale for further study (page 256). Working as a team, the two telescopes are rapidly enlarging and improving the picture of the universe which astronomers gradually have pieced together over the years. Knowledge of Universe Unfolds Thousands of years ago, on the plains of Asia Minor, shepherds watching the heavens at night noticed that some of the points of light moved with relation to the others. Slowly it came to be understood that these wanderers were the planets, traveling along regular orbits. Next it was discovered that the planets circled around the sun. Then it was realized that the sun was merely another star, like thousands of others visible in the night sky. Still later the astron * See "Mapping the Unknown Universe," by F. Barrows Colton, NATIONAL GEOGRAPHIC MAGAZINE, September, 1950.