Solar cycle 25

Solar cycle 25 is the current solar cycle, the 25th since 1755, when extensive recording of solar sunspot activity began. It began in December 2019 with a smoothed minimum sunspot number of 1.8.[1] It is expected to continue until about 2030.[2][3]

Solar cycle 25
ISES Solar Cycle 25 Sunspot Number Progression and Predictions as of March 2022
Sunspot data
Start dateDecember 2019
Max count40.0
Max count monthSeptember 2021 (progressive)
Min count1.8
Cycle chronology
Previous cycleSolar cycle 24 (2008-2019)

Predictions

Widely varying predictions regarding the strength of cycle 25 ranged from very weak with suggestions of slow slide in to a Maunder minimum like state[4][5] to a weak cycle similar to previous cycle 24[6] and even a strong cycle.[7][8][9] Upton and Hathaway predicted that the weakness of cycle 25 would make it part of the Modern Gleissberg Minimum.[4] One published prediction (of a very weak cycle) was retracted due to fundamental errors.[10]

The Solar Cycle 25 Prediction Panel predicted in December 2019[11] that solar cycle 25 will be similar to solar cycle 24, with the preceding solar cycle minimum in April 2020 (± 6 months), and the number of sunspots reaching a (smoothed) maximum of 115 in July 2025 (± 8 months). This prediction is in line with the current general agreement in the scientific literature, which holds that solar cycle 25 will be weaker than average (i.e. weaker than during the exceptionally strong Modern Maximum).[6]

Cycle 25 predictions
Source Date Cycle max Cycle start Cycle end
Thompson, M.J. et al.[3] August 2014 Q4 2019
Zharkova, V. et al 2014, 2015.[12] (Northumbria U.) October 2014 65 (80% of cycle 24)
Upton, L.A. and Hathaway, D.H.[4] (Solar Observatories Group, Stanford University) December 2018 78 (95% of cycle 24) Late 2020 – Early 2021
Xu, J.C. et al.[7] (Chinese Academy of Sciences) August 2018 168.5 ± 16.3 (2024) October 2020
Bhowmik, P. and Nandy, D.[6] (IISER Kolkata) December 2018 124 ± 15 (2023–2025) 2020 after 2031
Ozguc, A. et al.[8] (Harvard U-ty) December 2018 154 ± 12 (2023.2±1.1)
NOAA / SSRC[13] April 2019 117 ± 23 (2023–2026) mid-2019 – late 2020
NASA[14] June 2019 70 ± 29 (30–50% lower than Cycle 24 (2025)) 2020
NOAA / SSRC (update)[15] December 2019 115 ± 10 (July 2025) April 2020 (± 6 months)
Mcintosh et al..[16][17] June 2020 229 ± 25
Mcintosh et al.[16][17] December 2020 190 ± 20
National Center for Atmospheric Research[18] December 2020 233
(Actual) present >40.0 December 2019 -

Early signs
Time vs. solar latitude diagram of the radial component of the solar magnetic field (supersynoptic map or “butterfly” diagram) for cycle 24 based on the (zero-point corrected) integer rotation synoptic maps from GONG. Blue/red show negative/positive polarity fields scaled between ±5 Gauss. Two black arrows mark approximate location of two latitudinal bands of cycle 25. Data are acquired by GONG instruments operated by NISP/NSO/AURA/NSF.

As of April 2018, the Sun showed signs of a reverse magnetic polarity sunspot appearing and beginning this solar cycle.[19] It is typical during the transition from one cycle to the next to experience a period where sunspots of both polarities exist (during the solar minimum). The polarward reversed polarity sunspots suggest that a transition to cycle 25 is in process.[20] The first cycle 25 sunspot may have appeared in early April 2018[21][22] or even December 2016.[20]

In November 2019, two reversed polarity sunspots appeared, possibly signaling the onset of cycle 25.[23][24]

Nandy et al., analyzed the polarity orientation of bipolar magnetic regions observed in December 2019 and concluded that magnetic regions with the underlying orientation of solar cycle 25 toroidal field component were brewing in the solar convection zone, representing early signs of the new cycle.[25]

Supersynoptic (time vs. solar latitude) map of the radial component of the solar magnetic field for cycles 24-25 based on observations from the Global Oscillations Network Group (GONG) shows magnetic activity of cycle 25 beginning November 2019 at about 30 degree latitudes in both solar hemispheres.[26] A more recent supersynoptic map is available.[27]

Spotless days by year (Solar cycle 25 vs 24)

  • 2021 : 64 (18%)
  • 2020 : 192 (52%)
  • 2019 : 274 (75%)
  • 2018 : 208 (57%)
  • 2017 : 96 (26%)
  • 2016 : 27 (7%)
  • 2015 : 0 (0%)
  • 2014 : 1 (0%)
  • 2013 : 0 (0%)
  • 2012 : 0 (0%)
  • 2011 : 2 (1%)
  • 2010 : 44 (12%)
  • 2009 : 262 (72%)
  • 2008 : 265 (72%)
  • 2007 : 163 (45%)
  • 2006 : 65 (18%)

Events
Solar flares by year
1
2
3
4
5
6
7
8
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
  •   M5-M9
  •   X1-X5
  •   X5-X9
The strongest flares of Solar Cycle 25 (above M5.0 class) and related events
ClassYearDateSunspot regionRadio B.SR StormCMEGM Storm
X2.252022Apr 202992R3-Yes-
X1.592021Jul 32838R3-Yes-
X1.382022Mar 302975R3-YesG1
X1.172022Apr 172994R3-Yes-
X1.132022Apr 302994R3-Yes-
X1.02021Oct 282887R3S1Yes-
M9.672022Mar 312975R2-Yes-
M9.662022Apr 212993R2-Yes-
M7.292022Apr 202992R2-Yes-
M5.52022Jan 202929R2S1Yes-

2020
Solar flares in 2020[28]
10
20
30
40
50
60
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
  •   C
  •   M
  •   X

On 29 May, the first C-class solar flares of Solar Cycle 25 took place, as well as the first M-class flare. Solar activity continued to increase in the following months, especially abruptly in October, with flares taking place on a near-daily basis by November. On 29 November, an M4.4 flare, the strongest of the cycle to date, took place, possibly indicating the solar cycle would be more active than initially thought.[29]

On 8 December, a small coronal mass ejection was found heading directly towards Earth shortly after a strong C-class solar flare, hitting the planet on 9-10 December and causing bright aurorae at high latitudes.[30][31]

2021
Solar flares in 2021[32]
50
100
150
200
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
  •   C
  •   M
  •   X

The first X-class solar flare of the cycle took place on 3 July, peaking at X1.59.[33]

On 22 July, a total of six different active regions were seen on the solar disk for the first time since 6 September 2017.[34]

On 9 October, a M1.6 class solar flare erupted sending a coronal mass ejection that hit earth on 12 October triggering a (moderate) G2 geomagnetic storm.[35]

The second X-class flare of the solar cycle erupted on 28 October, producing a CME and a S1 solar radiation storm.[36] Reports initially predicted that the CME could graze Earth,[36] however geomagnetic storms on 30-31 October only reached a moderate Kp index of 4.[37]

On 3 and 4 November, the Kp index reached 8-, equivalent to a G4 geomagnetic storm.[38] This was the most intense geomagnetic storm to hit Earth since September 2017.

2022
Solar flares in 2022[39]
50
100
150
200
250
300
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
  •   C
  •   M
  •   X

In late March, sunspot region 2975 released X1.3 and M9.6 flares, the former causing a G1 geomagnetic storm on 31 March despite being near the solar limb.[40] The region rotated out of view of Earth on 5 April, but helioseismic measurements on April 8 showed it still active on the far side of the Sun.[41] On 12 April, a Coronal Mass Ejection on the far side likely erupted from the region,[42] with helioseismic measurements showing the region to have intensified since crossing over the limb. As the region began rotating into view from Earth, a possibly X-class flare occurred on 15 April.[43]

After rotating to the visible hemisphere of the Sun, the regions of the sunspot complex were designated 2993 through 2996. On 17 April, sunspot group 2994 released an X1.2 flare.[44][45] However, the complex's activity subsided slightly in the next few days.[46] While crossing the solar limb, sunspot region 2992 emitted M7.3 and X2.2 flares, the latter being the strongest of the cycle yet.[46]

See also

References
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  2. Odenwald, Sten (2 September 2016). "Waiting for the next sunspot cycle: 2019-2030". The Huffington Post. Retrieved 22 November 2017.
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  4. Upton, Lisa A.; Hathaway, David H. (28 August 2018). "An updated solar cycle 25 prediction with AFT: The modern minimum". Geophysical Research Letters. 45 (16): 8091–8095. arXiv:1808.04868. Bibcode:2018GeoRL..45.8091U. doi:10.1029/2018GL078387. S2CID 118913702.
  5. Kitiashvili et al.
  6. Bhowmik, Prantika; Nandy, Dibyendu (6 December 2018). "Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions". Nature Communications. 9 (1): 5209. arXiv:1909.04537. Bibcode:2018NatCo...9.5209B. doi:10.1038/s41467-018-07690-0. PMC 6283837. PMID 30523260.
  7. Li, F.Y.; Kong, D.F.; Xie, J.L.; Xiang, N.B.; Xu, J.C. (December 2018). "Solar cycle characteristics and their application in the prediction of cycle 25". Journal of Atmospheric and Solar-Terrestrial Physics. 181: 110–115. Bibcode:2018JASTP.181..110L. doi:10.1016/j.jastp.2018.10.014.
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