Solar cycle 1

Solar activity from February 1755 to June 1766

Solar cycle 1
Sunspot data
Start date	February 1755
End date	June 1766
Duration (years)	11.3
Max count	144.1
Max count month	June 1761
Min count	14.0
Cycle chronology
Next cycle	Solar cycle 2 (1766–1775)

Solar cycle 1 was the first solar cycle during which extensive recording of solar sunspot activity took place.^[1]^[2] The solar cycle lasted 11.3 years, beginning in February 1755 and ending in June 1766. The maximum smoothed sunspot number observed during the solar cycle was 144.1 (June 1761), and the starting minimum was 14.0.^[3]

Solar cycle 1 was discovered by Johann Rudolph Wolf who, inspired by the discovery of the solar cycle by Heinrich Schwabe in 1843, collected all available sunspot observations going back to the first telescopic observations by Galileo. He was able to improve Schwabe's estimate of the mean length of the cycle from about a decade to 11.11 years.^[4] However, he could not find enough observations before 1755 to reliably identify cycles, hence the 1755–1766 cycle is conventionally numbered as cycle 1. Wolf published his results in 1852.^[5]

References

^ Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics. 205 (2): 383–401. Bibcode:2002SoPh..205..383K. doi:10.1023/A:1014296529097. S2CID 118144552.
^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
^ "SIDC Monthly Smoothed Sunspot Number". sidc.oma.be.
^ Clark, Stuart G. (2007). The Sun Kings. Princeton University Press. p. 73. ISBN 978-0691126609.
^ Letellier, Christophe (2013). Chaos in Nature. World Scientific. pp. 344–346. ISBN 978-9814374422.

Solar cycles

18th century

1740–1759	Solar cycle 1 (1755 Feb – 1766 Jun)
1760–1779	Solar cycle 2 (1766 Jun – 1775 Jun) Solar cycle 3 (1775 Jun – 1784 Sep)
1780–1799	Solar cycle 4 (1784 Sep – 1798 Apr) Solar cycle 5 (1798 Apr – 1810 Aug)

19th century

1800–1819	Solar cycle 6 (1810 Aug – 1823 May)
1820–1839	Solar cycle 7 (1823 May – 1833 Nov) Solar cycle 8 (1833 Nov – 1843 Jul)
1840–1859	Solar cycle 9 (1843 Jul – 1855 Dec) Solar cycle 10 (1855 Dec – 1867 Mar)
1860–1879	Solar cycle 11 (1867 Mar – 1878 Dec) Solar cycle 12 (1878 Dec – 1890 Mar)
1880–1899	Solar cycle 13 (1890 Mar – 1902 Jan)

20th century

1900–1919	Solar cycle 14 (1902 Jan – 1913 Jul) Solar cycle 15 (1913 Jul – 1923 Aug)
1920–1939	Solar cycle 16 (1923 Aug – 1933 Sep) Solar cycle 17 (1933 Sep – 1944 Feb)
1940–1959	Solar cycle 18 (1944 Feb – 1954 Apr) Solar cycle 19 (1954 Apr – 1964 Oct)
1960–1979	Solar cycle 20 (1964 Oct – 1976 Mar) Solar cycle 21 (1976 Mar – 1986 Sep)
1980–1999	Solar cycle 22 (1986 Sep – 1996 Aug) Solar cycle 23 (1996 Aug – 2008 Dec)