The solar cycle

APR 01, 1982

The mysteries of the 11‐year period of sunspot activity are yielding to new approaches, such as magnetic‐dynamo modeling and a seismology that can detect photosphere pulsations as small as a few meters in amplitude.

DOI: 10.1063/1.2915008

Gordon Newkirk

Kendrick Frazier

Nearly 140 years have elapsed since the German apothecary and amateur astronomer Samuel Heinrich Schwabe reported discovery of the solar cycle. “From my earlier observations,” Schwabe wrote in 1843, “it appears that there is a certain periodicity in the appearance of sunspots and this theory seems more and more probable from the results of this year.” Schwabe had been looking for new planets crossing the Sun’s disk. The day‐to‐day records of sunspots he kept for 18 years as part of that search led him to realize that solar behavior is cyclic.

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More about the Authors

Gordon Newkirk. Institut für Astronomie, Eidgenössische Technische Hochschule, Zürich, Switzerland.