Solar activity from September 1784 to April 1798
Solar cycle 4 |
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Sunspot data |
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Start date | September 1784 |
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End date | April 1798 |
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Duration (years) | 13.6 |
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Max count | 235.3 |
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Max count month | February 1788 |
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Min count | 15.9 |
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Cycle chronology |
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Previous cycle | Solar cycle 3 (1775–1784) |
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Next cycle | Solar cycle 5 (1798–1810) |
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Solar cycle 4 was the fourth solar cycle since 1755, when extensive recording of solar sunspot activity began.[1][2] The solar cycle lasted 13.6 years, beginning in September 1784 and ending in April 1798 (thus overlapping the Dalton Minimum). The maximum smoothed sunspot number observed during the solar cycle was 235.3 (in February 1788), and the starting minimum was 15.9.[3]
There are some recent speculations that cycle 4, the longest solar cycle since 1755, was actually two cycles, based on the appearance of new sunspots at high solar latitudes in 1793–1796 and a reconstruction of the sunspot butterfly diagram for cycles 3 and 4,[4][5] although total sunspot numbers only show a single-peaked distribution.[3]
See also
References
- ^ Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383–401.
- ^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
- ^ a b SIDC Monthly Smoothed Sunspot Number. "[1]"
- ^ Usoskin, I. G.; Mursula, K.; Arlt, R.; Kovaltsov, G. A. (2009). "A Solar Cycle Lost in 1793–1800: Early Sunspot Observations Resolve the Old Mystery". The Astrophysical Journal. 700 (2): L154. arXiv:0907.0063. Bibcode:2009ApJ...700L.154U. doi:10.1088/0004-637X/700/2/L154.
- ^ "Centuries-old sketches solve sunspot mystery", New Scientist, 1 August 2009, p. 10.
Solar cycles
18th century | 1740–1759 | - Solar cycle 1 (1755 Feb – 1766 Jun)
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1760–1779 | - Solar cycle 2 (1766 Jun – 1775 Jun)
- Solar cycle 3 (1775 Jun – 1784 Sep)
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1780–1799 | - Solar cycle 4 (1784 Sep – 1798 Apr)
- Solar cycle 5 (1798 Apr – 1810 Aug)
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19th century | 1800–1819 | - Solar cycle 6 (1810 Aug – 1823 May)
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1820–1839 | - Solar cycle 7 (1823 May – 1833 Nov)
- Solar cycle 8 (1833 Nov – 1843 Jul)
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1840–1859 | - Solar cycle 9 (1843 Jul – 1855 Dec)
- Solar cycle 10 (1855 Dec – 1867 Mar)
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1860–1879 | - Solar cycle 11 (1867 Mar – 1878 Dec)
- Solar cycle 12 (1878 Dec – 1890 Mar)
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1880–1899 | - Solar cycle 13 (1890 Mar – 1902 Jan)
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20th century | 1900–1919 | |
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1920–1939 | |
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1940–1959 | |
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1960–1979 | |
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1980–1999 | |
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21st century | |
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