Solar cycle 9

Solar activity from July 1843 to December 1855

Solar cycle 9
The Sun in 1845, during solar cycle 9
Sunspot data
Start date	July 1843
End date	December 1855
Duration (years)	12.4
Max count	219.9
Max count month	February 1848
Min count	17.6
Spotless days	655
Cycle chronology
Previous cycle	Solar cycle 8 (1833–1843)
Next cycle	Solar cycle 10 (1855–1867)

Solar cycle 9 was the ninth solar cycle since 1755, when extensive recording of solar sunspot activity began.^[1]^[2] The solar cycle lasted 12.4 years, beginning in July 1843 and ending in December 1855. The maximum smoothed sunspot number observed during the solar cycle was 219.9 (February 1848), and the starting minimum was 17.6.^[3] During the solar cycle minimum transit from solar cycle 9 to solar cycle 10, there were a total of 655 days with no sunspots.^[4]^[5]^[6]

Solar cycle 9 began in 1843, the year that Heinrich Schwabe discovered the sunspot cycle.^[7] During this cycle, Edward Sabine, Rudolf Wolf, and other scientists recognized that solar disturbances affected the Earth's magnetic environment, so that solar cycles are identical to the Earth's geomagnetic cycles. Wolf also introduced the Wolf number during this period.

The phenomenon now known as geomagnetically induced current was seen for the first time during this cycle – it became apparent on the emerging electric telegraph network. Francis Ronalds, Honorary Director of the Kew Observatory and Sabine's colleague, received data from telegraph operators on the movements of their magnetic needles for comparison with his own photo-recordings of atmospheric electricity and geomagnetic intensity variations but had insufficient resources to study the causes of the unexpected currents in detail.^[8]^[9]

Geomagnetic activity during solar cycle 9 followed a double-peaked distribution, with more magnetic storms during the rising (1847–48) and falling (1851–54) parts of the cycle.^[10]

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. "[1]"
^ Spotless Days. "[2]"
^ Dr. Tony Phillips (11 July 2008). "What's Wrong with the Sun? (Nothing)". NASA. Archived from the original on 14 July 2008.
^ Solaemon's Spotless Days Page. "[3]"
^ Claudio Vita-Finzi. Solar History: An Introduction, p. 4, Springer, 2012 ISBN 9400742959.
^ Ronalds, B.F. (2016). Sir Francis Ronalds: Father of the Electric Telegraph. London: Imperial College Press. ISBN 978-1-78326-917-4.
^ Ronalds, B.F. (2016). "Sir Francis Ronalds and the Electric Telegraph". The International Journal for the History of Engineering & Technology. 86: 42–55. doi:10.1080/17581206.2015.1119481. S2CID 113256632.
^ Nevanlinna, H.; Ketola, A.; Häkkinen, L.; Viljanen, A.; Ivory, K. (23 April 1993). "Geomagnetic activity during solar cycle 9 (1844–1856)". Geophysical Research Letters. 20 (8): 743–746. Bibcode:1993GeoRL..20..743N. doi:10.1029/93GL00836.

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)