The Day We Found the Universe - Marcia Bartusiak [87]
Van Maanen was drawn as a student toward this line of work, an endeavor that other astronomers tried to avoid because of the tedium and difficulty in discerning the change in a star's position over time. The procedure involved comparing, with intense concentration, photographic plates taken over intervals of months or years. But to van Maanen the routine was heaven; he even went back to the pursuit two years before his death. “One always returns to one's first love,” he scribbled on a copy of his 1944 paper on stellar parallaxes. To carry out the task, he superimposed the pictures of the stars taken at different times in his special stereocomparator (more often called the “Blink”). This machine allowed the viewer to quickly alternate between two photographic plates taken of the same field at different times. The blinking proceeded so rapidly that an object that had moved between pictures would immediately stand out, while those that remained fixed appeared still. Van Maanen could then slowly turn a micrometer screw to measure the star's exact advancement across the sky. The number of turns measured off the change in the star's position—the amount the star had moved over the years. It was his most cherished instrument at the observatory's Pasadena headquarters, and everyone knew it: The warning “Do not use this stereocomparator without consulting A. van Maanen” was blatantly posted on its front. The sign remained there for decades, long after he had left.
Sociable and well-liked, “Van,” as everyone called him, played a good game of tennis and made sure newcomers to the mountain felt right at home. He was a lively storyteller and also a bit of a playboy. Once Shapley arrived, he and van Maanen became fast friends, as they were nearly the same age. “He could go to a dinner and soon have the whole table laughing,” recalled Shapley. An accomplished chef, van Maanen relished throwing parties where he could put his culinary skills into practice and prepare fine dishes for his cohorts. Shapley and van Maanen further bonded when they discovered they were both disliked by Adams, who was suspicious of them for their liberal outlooks and ambivalence toward the ongoing war in Europe, as well as their ambitions. “Van Maanen and I are in ill-favor because we do or try to do too much,” confided Shapley to a friend.
One of van Maanen's first jobs at Mount Wilson was to measure photographs of spectra taken over the face of the Sun, an endeavor that helped Hale map the Sun's magnetic field. Early reports suggested that the strength of the magnetic field varied with solar latitude, and van Maanen always seemed to see this effect, even though it was later found to be a mistake. Van Maanen's persistence in finding the change was a harbinger of trials to come in succeeding years—not concerning the Sun but rather the spiral nebulae.
Van Maanen first got involved with the spirals in late 1915, when George Ritchey asked him a favor. Ritchey was then using Mount Wilson's 60-inch telescope to produce superb photographs of spiral nebulae. Everyone agreed the images were breathtakingly beautiful. Part of this success was due to Ritchey's inventiveness. He had developed a fast camera shutter, which allowed him to build up an image from a series of short exposures, each taken when the atmosphere was calm. The total exposure time could last anywhere from two hours to more than eight hours, sometimes stretched over two or three nights. This resulted in rich nebular details never before captured.
When he approached van Maanen, Ritchey had