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2000-19 FOR IMMEDIATE RELEASE: June 22, 2000

100-Year-Old "Butterfly Diagram" Shows Sunspot Travel

David Hosansky
UCAR Communications
P.O. Box 3000
Boulder, CO 80307-3000
Telephone: (303) 497-8611
Fax: (303) 497-8610
E-mail: hosansky@ucar.edu

BOULDER -- A 1904 chart, known as the Maunder butterfly diagram because of its resemblance to three butterflies heading west, demonstrated for the first time the movement of sunspot formations from the poles toward the equator over the sun's 11-year activity cycle. The discovery blew holes in the solar theories of the time, and even today--a century later--theorists have not developed a full explanation of why spots move toward the solar equator. At this month's meeting of the American Astronomical Society in Rochester, New York, scientist Thomas Bogdan of the National Center for Atmospheric Research described how the chart ended up in Climax, Colorado, at the height of World War II. Housed at NCAR for 50 years, it has been restored for viewing. NCAR's primary sponsor is the National Science Foundation.

Bogdan, an NCAR scientist since 1983, is researching the history of NCAR's High Altitude Observatory, in hopes of writing a book. "For 17 years I walked by this picture of "butterflies" in a kind of cheesy frame and never gave it much thought," says Bogdan. "I only came to appreciate its significance while working on the HAO history." He has made an archival-quality print and is having the original reframed using acid-free paper and ultraviolet-resistant glass. "Since it survived the perils of the 20th century," he says, "it's fitting that it should be ready for the 21st."

E. Walter and Annie S.D. Maunder, who drew the chart, certainly knew their sunspots. Walter Maunder was an assistant in the solar department of the Greenwich Royal Observatory in England; he had been photographing the sun since the department was founded in 1873. Annie worked with Walter at the observatory as a "lady computer" from 1891 until they married in 1895. An unusually well-educated woman for her time, she had passed the Cambridge University degree examinations with honors in mathematics, though she was not allowed to receive a degree. Although Annie was required to resign when she married her boss, the two continued to work together on their own. In fact, Annie accompanied Walter on eclipse expeditions and developed a camera for photographing the corona. Walter died in 1928.

In 1943, while London was being bombed nightly by the Germans, Annie got a letter from a friend named Stephen Ionides. Born in London, Ionides had led an adventurous life as an engineer and miner in England, Australia, Mexico, and the American West before settling in Denver. Ionides' hobby was science history, and he asked Annie for one of her and her husband's drawings. To save the butterfly chart from destruction in the Blitz, she gave it to Ionides.

Later that year, Ionides attended a talk by a young astronomer from Climax, Colorado--Walter Orr Roberts, the founder of HAO. Ionides invited Roberts to his home, where Roberts saw the butterfly. "Walt was totally overwhelmed, because he understood the significance of it," says Bogdan. A few days later, Ionides mailed the chart to Roberts, saying it should be on display. Annie Maunder later wrote to Roberts, saying how glad she was that the chart had a safe home. She died in 1947. When HAO became part of NCAR in 1960, so did the chart.

NCAR is managed by the University Corporation for Atmospheric Research, a consortium of more than 60 universities offering Ph.D.s in atmospheric and related sciences.

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A butterfly-like pattern in the 1904 diagram shows the motion of sunspots toward the solar equator.

-The End-

Writer: Carol Rasmussen

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