Maunder Minimum

The Maunder Minimum, also known as the "prolonged sunspot minimum", is the name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time.

The term was introduced after John A. Eddy published a landmark 1976 paper in Science. Astronomers before Eddy had also named the period after the solar astronomers Annie Russell Maunder (1868–1947) and E. Walter Maunder (1851–1928), who studied how sunspot latitudes changed with time. The period which the husband and wife team examined included the second half of the 17th century.

Two papers were published in Edward Maunder's name in 1890 and 1894, and he cited earlier papers written by Gustav Spörer. Because Annie Maunder had not received a university degree (due to restrictions at the time), her contribution was not publicly recognized.

Spörer noted that, during a 28-year period (1672–1699) within the Maunder Minimum, observations revealed fewer than 50 sunspots. This contrasts with the typical 40,000–50,000 sunspots seen in modern times.

Like the Dalton Minimum and Spörer Minimum, the Maunder Minimum coincided with a period of lower-than-average European temperatures.

The Maunder Minimum occurred between 1645 and 1715 when very few sunspots were observed. This was not due to a lack of observations; during the 17th century, Giovanni Domenico Cassini carried out a systematic program of solar observations at the Observatoire de Paris, thanks to the astronomers Jean Picard and Philippe de La Hire. Johannes Hevelius also performed observations on his own. The total numbers of sunspots (but not Wolf numbers) in different years were as follows:

During the Maunder Minimum enough sunspots were sighted so that 11-year cycles could be extrapolated from the count. The maxima occurred in 1676, 1684, 1695, 1705 and 1716.

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