George Ellery Hale (June 29, 1868 – February 21, 1938) was an American astrophysicist best known for his discovery of magnetic fields in sunspots. He was also a key figure in the planning and construction of several world-leading telescopes: the 40-inch refracting telescope at Yerkes Observatory; the 60-inch Hale and 100-inch Hooker reflecting telescopes, both at Mount Wilson Observatory; and the 200-inch Hale reflecting telescope at Palomar Observatory. He played a key role in the foundation of the International Union for Cooperation in Solar Research and the National Research Council, and in developing the California Institute of Technology into a leading research university.
Early life and education George Ellery Hale was born on June 29, 1868, in Chicago, Illinois, to William Ellery Hale and Mary Browne. He is descended from Thomas Hale of Watton-on-Stone, Hertfordshire, England, whose son emigrated to America about 1640. His father acquired a considerable fortune manufacturing and installing passenger elevators during the reconstruction of Chicago, which had been destroyed in the Great Chicago Fire of 1871. The oldest of three children who lived past childhood, George received strong encouragement from his father, who supported the boy's active mind and curiosity, and his mother, who inculcated in him a love of poetry and literature. He spent his youth fascinated by the books and machinery given to him by his parents—one of his most prized possessions was a small microscope. With his father's encouragement, he built a small shop in their house that turned into a laboratory. The microscope led to his interest in optics. At the age of fourteen, George built his first telescope. His father later replaced it with a second-hand Clark refractor that they mounted on the roof of their Kenwood house. Soon he was photographing the night skies, observing a partial eclipse of the Sun, and drawing sunspots. As an avid reader with a strong interest in the budding field of astrophysics, Hale was drawn to the writings of William Huggins, Norman Lockyer, and Ernest Rutherford. His fascination with science, however, did not preclude interests more typical of a normal boy, such as fishing, boating, swimming, skating, tennis, and bicycling. He was an enthusiastic reader of the stories of Jules Verne—particularly drawn to the tales of adventure set in the mountains of California. Hale spent summers at his grandmother's house in the old New England village of Madison, Connecticut, where he met his future wife, Evelina Conklin. After graduating from Oakland Public School in Chicago, Hale attended the Allen Academy, where he studied chemistry, physics, and astronomy. He supplemented his practical home experience by attending a course in shop-work at the Chicago Manual Training School. During these years, Hale developed a knowledge of the principles of architecture and city planning with the help of his father's friend, well-known architect Daniel Burnham. Upon Burnham's advice and encouragement, Hale decided at the age of seventeen to continue his education at the Massachusetts Institute of Technology (MIT). Hale was educated at MIT, at the Harvard College Observatory, (1889–90), and in Berlin (1893–94) where he was a PhD student but never finished his degree. At the time he already had an appointment as a professor at the recently established University of Chicago. As an undergraduate at MIT, he is known for inventing the spectroheliograph, with which he made his discovery of solar vortices.
Research
In 1890, he began research at the Kenwood Astrophysical Observatory, which Hale's father had built for him; he was professor of astrophysics at Beloit College (1891–93); associate professor at the University of Chicago until 1897, and full professor (1897–1905). He was coeditor of Astronomy and Astrophysics, 1892–95, and after 1895 editor of the Astrophysical Journal. He also served on the board of trustees for Science Service, now known as Society for Science & the Public, from 1921 to 1923. In 1908, he used the Zeeman effect with a modified spectroheliograph to establish that sunspots were magnetic. Subsequent work demonstrated a strong tendency for east-west alignment of magnetic polarities in sunspots, with mirror symmetry across the solar equator; and that the polarity in each hemisphere switched orientation from one sunspot cycle to the next. This systematic property of sunspot magnetic fields is now commonly referred to as the "Hale–Nicholson law," or in many cases simply "Hale's law." Hale spent a large portion of his career trying to find a way to image the solar corona without the benefit of a total solar eclipse, but this was not achieved until the work of Bernard Lyot. In October 1913, Hale received a letter from Albert Einstein, asking whether certain astronomical observations could be done that would test Einstein's hypothesis concerning the effects of gravity on light. Hale replied in November, saying that such observations could be done only during a total eclipse of the Sun.
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