Solar cycle 18

Solar activity from February 1944 to April 1954

Solar cycle 18
Sunspot data
Start date	February 1944
End date	April 1954
Duration (years)	10.2
Max count	218.7
Max count month	May 1947
Min count	12.9
Spotless days	446
Cycle chronology
Previous cycle	Solar cycle 17 (1933–1944)
Next cycle	Solar cycle 19 (1954–1964)

Solar cycle 18 was the eighteenth solar cycle since 1755, when extensive recording of solar sunspot activity began.^[1]^[2] The solar cycle lasted 10.2 years, beginning in February 1944 and ending in April 1954. The maximum smoothed sunspot number observed during the solar cycle was 218.7 (May 1947), and the starting minimum was 12.9.^[3] During the minimum transit from solar cycle 18 to 19, there were a total of 446 days with no sunspots.^[4]^[5]^[6]

Cycle 18 was characterized by "giant" sunspots.^[7] The recording of the 10.7 cm (2800 MHz) solar radio flux began partway during this cycle,^[8] and values of the solar flux during this cycle turned out to be particularly high.^[7]

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]"
^ ^a ^b Dodson, Helen W.; Hedeman, E. Ruth; Mohler, Orren C. (August 1974). "Comparison of activity in solar cycles 18, 19, and 20". Reviews of Geophysics. 12 (3): 329–341. Bibcode:1974RvGSP..12..329D. doi:10.1029/RG012i003p00329.
^ Petersen, Edward (2012). Single Event Effects in Aerospace. Wiley. p. 20. ISBN 978-1118084304.

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)