National Geographic : 1956 Dec
MULV~t Ckm~xts t LbmVlcse By Ira Sprague Bowen, Ph.D. Director of Mount Wilson and Palomar Observatories 780 DAYBREAK comes early on Palomar Mountain. On this particular morning, May 11, 1956, there was a light frost on the cedars and sparse grasses that grow more than a mile above sea level on the California moun taintop. The rising sun outlined first the 135-foot high silver dome of the world's largest tele scope, the great 200-inch Hale. In a twin kling it caught a smaller dome close by that houses the wide-seeing Big Schmidt telescope, as remarkable in its own way as the Hale. Star Portraits in Red and Blue This daily miracle of sunrise on Palomar Mountain was lost on George O. Abell, the young astronomer of the National Geographic Society-Palomar Observatory Sky Survey. He was deep below the dome of the Big Schmidt in his darkroom, developing two 14-inch square photographic plates made through the telescope in the hours just before dawn. One plate was sensitive to red light, the other to blue. If all had gone well during his lonely vigil, if there were no faults in the emulsion, if the delicate focus adjustment of the Big Schmidt had been precise, and if there had been no failure in tracking the guide star, then the chances were good that George Abell would have something. He would have captured, in incredible detail and clarity, an area of the sky as large as the bowl of the Big Dipper. He would have penetrated space to an approximate depth of 6,000,000,000,000,000,000,000 (six sextillion) miles-one billion light-years. If the area covered by the plates was typi cal, he would have fixed, for men to study and try to understand, hundreds of thousands of individual stars and probably an even greater number of galaxies-entire systems of stars in space. Abell gave the plates a cursory but prac ticed examination. They were good. He switched off the lights and moved across the hall to his small office. Above his desk on the wall hung a dome shaped chart marked with squares and ob longs, each representing a section of the sky, and together covering some three-fourths of the whole celestial sphere. Unlike everything else in his trim office, the chart was smudged and well worn. It had been on the wall a long time. Every square and oblong had been penciled in-save one. It showed white and bare (opposite). Abell picked up his blue pencil and quickly closed the square with the hen tracks of celes tial positions: right ascension, 13 hours 36 minutes; declination, plus 480. Then he pulled on his heavy mackinaw, flipped the lights, slammed the door to the dome, and strode off across the field toward the "monas tery," where tired Palomar astronomers sleep after their nightly labors. If his step was unusually springy as he moved across the field, and if he made a little too much noise as he entered the monastery that bright frosty morning, I think George Abell can be forgiven. After nearly seven years of work, shared by all of us at Palomar, he had completed observations for the National Geographic Society-Palomar Observatory Sky Atlas.* Wide Eye of Palomar Scans the Skies The 48-inch Big Schmidt, the telescope that made the Sky Atlas, is actually a gigantic wide-angle camera. Its name honors the late Bernhard Schmidt, the German optical pio neer who invented a correcting lens that made it possible to photograph large areas of the sky with virtually no distortion. Whereas the 200-inch Hale telescope at Palomar sees an area of sky only as large as a quarter of the full moon, the Schmidt's wide *See, in the NATIONAL GEOGRAPHIC MAGAZINE: "Our Universe Unfolds New Wonders," by Albert G. Wilson, February, 1952; and "Mapping the Un known Universe," by F. Barrows Colton, September, 1950.