The Day We Found the Universe - Marcia Bartusiak [105]
Shapley proceeded to estimate the distance of NGC 6822 by comparing its size and the observed magnitudes of its brightest stars to that of the Large Magellanic Cloud. Interestingly, he arrived at a distance of about a million light-years. “It appears to be a great star cloud that is at least three or four times as far away as the most distant of known globular clusters and probably quite beyond the limits of the galactic system,” reported Shapley in his observatory's December 1923 Bulletin. A news report by Science Service promptly called it “the most distant object seen by man, another universe of stars.” NGC 6822 wasn't a spiral nebula, but it certainly offered Shapley proof that large stellar systems existed beyond the Milky Way. Yet, for Shapley, his distance calculation for this stellar cloud simply had no bearing on the question of the spirals. For those he tenaciously held fast to his convictions and continued to spread the word in various publications that spiral nebulae were “neither galactic in size nor stellar in composition.”
Hubble obtained more than fifty photographs of NGC 6822 over time and found fifteen variable stars. “Eleven…are clearly Cepheids,” he eventually reported two years later. Using them as standard candles, Hubble calculated a distance of some 700,000 light-years, which was undoubtedly beyond the borders of Shapley's newly supersized Milky Way. “N.G.C. 6822 lies far outside the limits of the galactic system,” stated Hubble, “and hence may serve as a stepping-stone for speculations concerning habitants of space beyond.” His early work on NGC 6822 likely gave Hubble the confidence that he could pursue Cepheids as distance markers in spiral nebulae, observations he was carrying out at the same time and would actually report on first.
Observing with the 100-inch was a choreographed dance within the monumental dome a hundred feet high and nearly as wide. Sometimes Hubble could just lean back in a bentwood chair, his favorite, and serenely smoke his pipe in the darkness while taking a photograph. But other times he was perched high in the air on a platform that could adjust to any height via rails set on either side of the dome opening. With the telescope's clock drive shifting the telescope as the nighttime sky slowly moved overhead, he and his assistant made sure the advance stayed in synchrony with Earth's rotation. At the same time, they had to keep the dome rotated and the platform height adjusted, so that the telescope kept spying on the cosmos and not an inside wall. “This was the astronomical observing experience at its best,” noted Mount Wilson astronomer Allan Sandage, “a dark, quiet dome, a silently moving monster telescope, and mastery of the dangerous…platform, all in the interest of collecting data on a problem of transcendental significance.” Night after night, the cosmic waltz went on. If Hubble got clouded out, he had a backup: “You begin with deskwork, later you turn to heavy reading, and later, to a detective story,” he said.
Edwin Hubble observing at the 100-inch, sitting on his
favorite bentwood chair (Reproduced by permission of the
Huntington Library, San Marino, California)
The only scheduled break was “lunch,” provided at midnight. In the early years, it was simply hardtack and cocoa (Hale considered coffee “unwholesome”), served in a concrete bunker beneath the 60-inch. Later on, at a shack built halfway between the 60-and 100-inch, astronomers were offered two pieces of bread, two eggs, butter and jam, and a single cup of coffee or tea, a repast purposefully kept skimpy by the observatory's notoriously frugal administrator, Walter Adams. Hubble gained the respect of the night assistants when he washed his own dish afterward, giving