List of solar cycles

The following is a list of solar cycles (sometimes called sunspot cycles), tracked since 1755 following the original numbering proposed by Rudolf Wolf in the mid-19th century[1][2] The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO.[3] Sunspot number counts exist since 1610[4] but the cycle numbering is not well defined during the Maunder minimum.[5] It was proposed that one cycle might have been lost in the late 18th century,[6] but this still remains not fully confirmed.

The smoothing was done using the traditional SIDC smoothing formula.[7] Other smoothing formulas exist, and they usually give slightly different values for the amplitude and timings of the solar cycles. An example is the Meeus smoothing formula,[8] with related solar cycles characteristics available in this STCE news item.[9]

In the table below, the number of spotless days is the number between the maximum of the previous solar cycle and the maximum of the new solar cycle. As an example, there were 817 spotless days during the transit from solar cycle 23 to solar cycle 24.

Solar Cycle Start Smoothed minimum ISN Maximum Smoothed maximum ISN Time of Rise (years) Duration (years) Spotless days[10][11][12]
Solar cycle 1 1755 February 14.0 1761 June 144.1 6.3 11.3
Solar cycle 2 1766 June 18.6 1769 September 193.0 3.3 9.0
Solar cycle 3 1775 June 12.0 1778 May 264.3 2.9 9.3
Solar cycle 4 1784 September 15.9 1788 February 235.3 3.4 13.6
Solar cycle 5 1798 April 5.3 1805 February 82.0 6.8 12.3
Solar cycle 6 1810 August 0.0 1816 May 81.2 5.8 12.8
Solar cycle 7 1823 May 0.2 1829 November 119.2 6.5 10.5
Solar cycle 8 1833 November 12.2 1837 March 244.9 3.3 9.7
Solar cycle 9 1843 July 17.6 1848 February 219.9 4.6 12.4
Solar cycle 10 1855 December 6.0 1860 February 186.2 4.2 11.3 655
Solar cycle 11 1867 March 9.9 1870 August 234.0 3.4 11.8 406
Solar cycle 12 1878 December 3.7 1883 December 124.4 5.0 11.3 1028
Solar cycle 13 1890 March 8.3 1894 January 146.5 3.8 11.8 736
Solar cycle 14 1902 January 4.5 1906 February 107.1 4.1 11.5 934
Solar cycle 15 1913 July 2.5 1917 August 175.7 4.1 10.1 1023
Solar cycle 16 1923 August 9.4 1928 April 130.2 4.7 10.1 534
Solar cycle 17 1933 September 5.8 1937 April 198.6 3.6 10.4 568
Solar cycle 18 1944 February 12.9 1947 May 218.7 3.3 10.2 269
Solar cycle 19 1954 April 5.1 1958 March 285.0 3.9 10.5 446
Solar cycle 20 1964 October 14.3 1968 November 156.6 4.1 11.4 227
Solar cycle 21 1976 March 17.8 1979 December 232.9 3.8 10.5 272
Solar cycle 22 1986 September 13.5 1989 November 212.5 3.2 9.9 273
Solar cycle 23 1996 August 11.2 2001 November 180.3 5.3 12.3 309
Solar cycle 24 2008 December 2.2 2014 April 116.4 5.3 In progress 817
Solar cycle 25 First spot[13] 137
Average 9.3 178.7 4.4 11.04

References

  1. ↑ Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383-401.
  2. ↑ "Did You Say the Sun Has Spots?". Space Today Online.
  3. ↑ "Sunspot numbers". WDC-SILSO. Royal Observatory of Belgium. Retrieved 19 May 2017.
  4. ↑ Hathaway,, D. (2015). "The solar cycle". Living Reviews in Solar Physics. 12: 4. arXiv:1502.07020. Bibcode:2015LRSP...12....4H. doi:10.1007/lrsp-2015-4.
  5. ↑ "The Maunder minimum".
  6. ↑ Usoskin; et al. "A solar cycle lost in 1793-1800: Early sunspot observations resolve the old mystery". Astrophys. J. Lett. 700: L154. arXiv:0907.0063. Bibcode:2009ApJ...700L.154U. doi:10.1088/0004-637X/700/2/L154.
  7. ↑ "SIDC smoothing formula". WDC-SILSO. Royal Observatory of Belgium. Retrieved 19 May 2017.
  8. ↑ Meeus, J. (1958). "Une formule d'adoucissement pour l'activité solaire". Ciel et Terre. 74: 445. Bibcode:1958C&T....74..445M.
  9. ↑ "The solar cycle's new clothes". STCE. Royal Observatory of Belgium. Retrieved 8 July 2015.
  10. ↑ "Spotless Days". SpaceWeather.com. Retrieved 29 July 2014.
  11. ↑ "What's Wrong with the Sun?". NASA Science. NASA. Retrieved 29 July 2014.
  12. ↑ "Spotless Days Page". SILSO. Royal Observatory of Belgium. Retrieved 3 April 2017.
  13. ↑ "The first sunspot of cycle 25 is seen!". STCE. Royal Observatory of Belgium. Retrieved 22 December 2016.
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