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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〔Bruce Weber, (John A. Eddy, Solar Detective, Dies at 78 ), ''New York Times,'' June 17, 2009 (retrieved 28 July 2015)〕 published a landmark 1976 paper in ''Science''.〔 (PDF Copy )〕 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.〔(Who named the Maunder Minimum? )〕 The period 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〔E.W.M. (1890) ("Professor Spoerer's researches on sun-spots," ) ''Monthly Notices of the Royal Astronomical Society'', 50 : 251-252.〕 and 1894,〔E. Walter Maunder (August 1, 1894) ("A prolonged sunspot minimum," ) ''Knowledge'', 17 : 173-176.〕 and he cited earlier papers written by Gustav Spörer.〔See: * Spörer (1887) ("Über die Periodicität der Sonnenflecken seit dem Jahre 1618, vornehmlich in Bezug auf die heliographische Breite derselben, und Hinweis auf eine erhebliche Störung dieser Periodicität während eines langen Zeitraumes" ) (On the periodicity of sunspots since the year 1618, especially with respect to the heliographic latitude of the same, and reference to a significant disturbance of this periodicity during a long period), ''Vierteljahrsschrift der Astronomischen Gesellschaft (Leipzig)'', 22 : 323-329. * G. Spoerer (February 1889) ("Sur les différences que présentent l'hémisphère nord et l'hémisphère sud du Soleil" ) (On the differences that the northern hemisphere and southern hemisphere of the sun present), ''Bulletin Astronomique'', 6 : 60-63.〕 Due to the social climate of the time, Annie's contribution was not publicly recognized.〔http://www.underthemicroscope.com/notable-irish-scientist-annie-maunder-the-lady-computer/〕 Spörer noted that, during one 28-year period within the Maunder Minimum (1672–1699), observations showed fewer than 50 sunspots, as opposed to a more typical 40,000–50,000 spots in modern times.〔(【引用サイトリンク】url=http://www.stsci.edu/stsci/meetings/lisa3/beckmanj.html )〕 Like the Dalton Minimum and Spörer Minimum, the Maunder Minimum coincided with a period of lower-than-average European temperatures. ==Sunspot observations== 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. The sunspot activity was then concentrated in the southern hemisphere of the Sun, except for the last cycle when the sunspots appeared in the northern hemisphere, too. According to Spörer's law, at the start of a cycle, spots appear at ever lower latitudes until they average at about latitude 15° at solar maximum. The average then continues to drift lower to about 7° and after that, while spots of the old cycle fade, new cycle spots start appearing again at high latitudes. The visibility of these spots is also affected by the velocity of the sun's surface rotation at various latitudes: Visibility is somewhat affected by observations being done from the ecliptic. The ecliptic is inclined 7° from the plane of the Sun's equator (latitude 0°). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「maunder minimum」の詳細全文を読む スポンサード リンク
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