Solar scientist John Allen Eddy died at his home in Tucson, Arizona, on 10 June 2009, following a long struggle with cancer. His groundbreaking studies have fundamentally changed our perception of the Sun’s behavior over the past few millennia.
Born in Pawnee City, Nebraska, on 25 March 1931, Jack graduated from Pawnee City High School in 1948; he was the only one of three siblings to attend college. His interest in astronomy was awakened during a celestial navigation course he took at the US Naval Academy, from which he graduated in 1953. Being punished for evading curfew to locate the obscure constellation Draco from the roof of the midshipmen’s residence taught Jack that too much zeal for science can be detrimental. After serving as an officer and navigator in Korea and in the Persian Gulf, he left the navy in 1957 for graduate school at the University of Colorado at Boulder. He earned a PhD in astrogeophysics in 1962, under the direction of Gordon Newkirk, for his analysis of sky brightness observed from 100 000-ft balloon altitudes.
Jack held a position with the High Altitude Observatory (HAO) in Boulder between 1963 and 1976, where he taught the solar physics course at the University of Colorado. There, he found that a historical approach provided an effective means of conveying new ideas. Archival records he consulted during his teaching awakened his interest in the Sun’s past erratic behavior and led him to further study. His influential 1976 Science cover article confirmed a virtual absence of sunspots between 1645 and 1715, which he termed the Maunder Minimum. His discovery upset the mainstream view that the Sun’s activity cycle was a roughly regular 11-year oscillation. His studies were based on pioneering use of historical evidence, including sunspot drawings by 17th-century astronomers like Johannes Hevelius, early sightings of the aurora, naked-eye observations of sunspots, and chronicles of solar eclipses.
Jack backed up and extended those visual observations with new evidence from carbon-14 in tree rings, from which solar activity variations can be deduced. Using that radioisotopic evidence, he found earlier periods of low activity such as a hiatus lasting from the mid-15th to mid-16th centuries, which he named after Gustav Spörer, a 19th-century German astronomer who was the first to notice the paucity of spots in the 17th century. The agreement in timing between those activity minima and the cooling of climate called the Little Ice Age continues to stimulate Sun–climate studies.
The findings about the Sun’s variability, together with Jack’s refreshing interdisciplinary outlook, reinvigorated solar research. They so caught the public imagination that for a few years, Jack’s was the most recognizable name in astronomy. He was an outstanding speaker, whose talks to the American Astronomical Society and at meetings of the American Geophysical Union were delivered to standing-room-only audiences. A talented popularizer, he spoke on Wall Street about sunspots and the stock market, and his findings appeared in TV Guide.
His skilled use of evidence from unconventional sources also served Jack well in his investigations of the Bighorn and Moose Mountain medicine wheels in Wyoming and Saskatchewan, Canada, respectively. His studies of their East–West alignment suggested a previously unappreciated influence of astronomy on the design of those structures. His findings on their astronomical significance were reported in a Science cover article in 1974.
Jack’s foundational work was all the more remarkable because it was carried out on his own time while he struggled to support his family during a period of funding cutbacks in the 1970s. Increasing recognition brought him chairmanships of national and international scientific committees, and his insightful leadership put the study of Sun–climate relations on a constructive course that continues today. His humor and talent at creating caricatures enlivened many long committee meetings; Jack coined the term “Scheherazades” for unnecessarily drawn-out scientific projects. He also likened the reception accorded to researchers venturing outside their specialization to the wariness that greeted explorers Meriwether Lewis and William Clark on their first encounter with the Mandan tribe in the American West.
Jack spent 1977–78 as a visitor at the Harvard–Smithsonian Center for Astrophysics, then went back to the HAO in Boulder from 1978 to 1985. He founded the Office for Interdisciplinary Earth Studies at the University Corporation for Atmospheric Research in 1986 and was its director until 1991. He used his management skills at a consortium of Michigan research institutions between 1992 and 1994, then focused his energy on environmental issues from 1994 to 2000 as cofounder and coeditor with his wife, Barbara, of the journal Consequences. He worked at the National Solar Observatory in Tucson from 2004 until his death.
The six books he edited and more than 150 scientific papers he wrote bear testimony to the lucidity and engaging style of Jack’s writing. His excellent use of historical data to attack current astronomical problems earned him the presidencies of the historical astronomy divisions of the American Astronomical Society between 1981 and 1983 and of the International Astronomical Union between 1985 and 1988. He received the Arctowski Medal from the National Academy of Sciences in 1987 and the 1983 James Arthur Prize of the Harvard–Smithsonian Center for Astrophysics.
Jack was a kind and thoughtful man whose mentoring opened up opportunities for several of us in the next generation. He has been a major figure in solar research, and his influence will long endure.
