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Solar cycle 19 was the nineteenth solar cycle since 1755, when extensive recording of solar sunspot activity began.〔Kane, R.P. (2002). "(Some Implications Using the Group Sunspot Number Reconstruction )". ''Solar Physics'' 205(2), 383-401.〕〔(【引用サイトリンク】 url=http://www.spacetoday.org/SolSys/Sun/Sunspots.html )〕 The solar cycle lasted 10.5 years, beginning in April 1954 and ending in October 1964. The International Geophysical Year occurred at the peak of this solar cycle. The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve-month period) observed during the solar cycle was 201.3, in March 1958 (the highest on record), and the minimum was 9.6.〔SIDC Monthly Smoothed Sunspot Number. "()"〕 There were a total of 227 days with no sunspots during this cycle.〔Spotless Days. "()"〕〔What's Wrong with the Sun? (Nothing) more information: Spotless Days. "()"〕〔Solaemon's Spotless Days Page. "()"〕 == Extreme events == A geomagnetic storm in February 1956 interfered with radio communications and prompted a search for the British submarine ''Acheron'' after it lost radio contact.〔(''Amsterdam Evening Recorder'', 24 February 1956 )〕 Intense red aurora displays frightened people in Europe on 11 February 1958 and were visible from many US cities as far South as the 40th parallel. This geomagnetic storm caused a radio blackout over North America. Aurora displays were visible over New York, on 13 November 1960 and 1 October 1961.〔http://www.solarstorms.org/SRefStorms.html〕 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「Solar cycle 19」の詳細全文を読む スポンサード リンク
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