Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to have started in 1755. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO.[1]
Sunspot counts exist since 1610[2] but the cycle numbering is not well defined during the Maunder minimum.[3] It was proposed that one cycle might have been lost in the late 18th century,[4] but this remains not fully confirmed.
Solar cycles can be reconstructed indirectly, using the radiocarbon 14C proxy, for the last millennium.[5]
The smoothing is done using the traditional SIDC smoothing algorithm.[6] Using this algorithm, if the month in question is notated month 0, a weighted average is formed of months −6 to 6, where months −5 to 5 are given weightings of 1, and months −6 and 6 are given weightings of 0.5. 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,[7] with related solar cycles characteristics available in this STCE news item.[8]
The start of solar cycle 25 was declared by SIDC on September 15, 2020 as being in December 2019.[9] This makes cycle 24 the only "11-year solar cycle" to have lasted precisely 11 years.
^"Sunspot numbers". WDC-SILSO. Royal Observatory of Belgium. Retrieved 19 May 2017.
^Hathaway, D. (2015). "The solar cycle". Living Reviews in Solar Physics. 12 (1): 4. arXiv:1502.07020. Bibcode:2015LRSP...12....4H. doi:10.1007/lrsp-2015-4. PMC 4841188. PMID 27194958.
^Usoskin; Mursula; Kovaltsov (2001). "Heliospheric modulation of cosmic rays and solar activity during the Maunder minimum". J. Geophys. Res. 106(A8) (A8): 16039. Bibcode:2001JGR...10616039U. doi:10.1029/2000JA000105.
^Usoskin; et al. (2009). "A solar cycle lost in 1793-1800: Early sunspot observations resolve the old mystery". Astrophys. J. Lett. 700 (2): L154. arXiv:0907.0063. Bibcode:2009ApJ...700L.154U. doi:10.1088/0004-637X/700/2/L154. S2CID 14882350.
^Usoskin; et al. "Solar cyclic activity over the last millennium reconstructed from annual 14C data". Astron. Astrophys. 649: A141. arXiv:2103.15112. doi:10.1051/0004-6361/202140711.
^"SIDC smoothing formula". WDC-SILSO. Royal Observatory of Belgium. Retrieved 19 May 2017.
^Meeus, J. (1958). "Une formule d'adoucissement pour l'activité solaire". Ciel et Terre. 74: 445. Bibcode:1958C&T....74..445M.
^"The solar cycle's new clothes". STCE. Royal Observatory of Belgium. Retrieved 8 July 2015.
^"December 2019 confirmed as starting point of the new solar activity cycle". SIDC.
and 30 Related for: List of solar cycles information
Solarcycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first...
solar cycle, with the flip occurring when the solarcycle is near its maximum. After two solarcycles, the Sun's magnetic field returns to its original...
addition to the ~11 year solarcycle, the intensity of the solar maxima can vary from cycle to cycle. When several solarcycles exhibit greater than average...
supplies. Solar variation Listofsolarcycles Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2)...
Solarcycle 23 was the 23rd solarcycle since 1755, when extensive recording ofsolar sunspot activity began. The solarcycle lasted 12.3 years, beginning...
Comparison with other cycles shows that geomagnetic activity during the declining phase ofcycle 20 (1973–1975) was unusually high. Heavy solar activity was a...
and 1 October 1961. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
number of 81.8. This maximum value was substantially lower than other recent solarcycles, down to a level which had not been seen since cycles 12 to 15...
hundreds of millennia) cyclesof subtle variation in the Earth's orbit (Milankovich cycles) affect the solar irradiance and insolation (but not the solar constant)...
beginning of systematic monitoring of the total solar irradiance from space. Solar variation Listofsolarcycles Kane, R.P. (2002). "Some Implications...
Solarcycle 25 is the current solarcycle, the 25th since 1755, when extensive recording ofsolar sunspot activity began. It began in December 2019 with...
starting minimum was 5.3. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
single-peaked distribution. Listofsolarcycles Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383–401...
core of the Sun is considered to extend from the center to about 0.2 ofsolar radius (139,000 km; 86,000 mi). It is the hottest part of the Sun and of the...
York on 3 April 1940. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
recognized that solar disturbances affected the Earth's magnetic environment, so that solarcycles are identical to the Earth's geomagnetic cycles. Wolf also...
starting minimum was 0.0. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
during this cycle, and values of the solar flux during this cycle turned out to be particularly high. Listofsolarcycles Kane, R.P. (2002), "Some Implications...
the Wilson effect. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
Solarcycle 3 was the third solarcycle since 1755, when extensive recording ofsolar sunspot activity began. The solarcycle lasted 9.3 years, beginning...
observed during the solarcycle was 119.2 (November 1829), and the starting minimum was 0.2. Listofsolarcycles Excerpts from Solar Observations During...
affected telegraph lines. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
radio transmission. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
building as glowing. Listofsolarcycles Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401...
recorded of any cycle transit to date). Strong auroral displays were observed in October 1870, February 1872, and August 1872. Listofsolarcycles Kane,...
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