Cycle Num: | 25 |
Start Date: | December 2019 |
End Date: | about 2030 |
Max Count: | 131.1 (smoothed) |
Max Count Date: | January 2024 (progressive)[1] |
Min Count: | 1.8 |
Prev Name: | Solar cycle 24 |
Prev Dates: | 2008–2019 |
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 minimum smoothed sunspot number of 1.8.[2] It is expected to continue until about 2030.[3] [4]
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[5] to a weak cycle similar to previous cycle 24 and even a strong cycle.[6] Upton and Hathaway predicted that the weakness of cycle 25 would make it part of the Modern Gleissberg Minimum.
The Solar Cycle 25 Prediction Panel predicted in December 2019[7] that solar cycle 25 will be similar to, 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).[8] However, observations from 2020 to 2022, the first three years of the cycle, significantly exceed predicted values.[9]
Thompson, M.J. et al. | August 2014 | Q4 2019 | |||
Zharkova, V. et al 2014, 2015.[10] (Northumbria U.) | October 2014 | 65 (80% of cycle 24) | |||
Upton, L.A. and Hathaway, D.H.[11] (Solar Observatories Group, Stanford University) | December 2018 | 78 (95% of cycle 24) | Late 2020 – Early 2021 | ||
Xu, J.C. et al.[12] (Chinese Academy of Sciences) | August 2018 | 168.5 ± 16.3 (2024) | October 2020 | ||
Bhowmik, P. and Nandy, D. (IISER Kolkata) | December 2018 | 124 ± 15 (2023–2025) | 2020 | after 2031 | |
Ozguc, A. et al.[13] (Harvard U-ty) | December 2018 | 154 ± 12 (2023.2±1.1) | |||
NOAA / SSRC[14] | April 2019 | 117 ± 23 (2023–2026) | mid-2019 – late 2020 | ||
NASA[15] | June 2019 | 70 ± 29 (30–50% lower than Cycle 24 (2025)) | 2020 | ||
NOAA / SSRC (update)[16] | December 2019 | 115 ± 10 (July 2025) | April 2020 (± 6 months) | ||
Mcintosh et al.[17] [18] | June 2020 | 229 ± 25 | |||
Mcintosh et al. | December 2020 | 190 ± 20 | |||
National Center for Atmospheric Research[19] | December 2020 | 233 | |||
de Jager, C. and Duhau, S. [20] | December 2020 | 160 ± 8 (2025 ± 1) | |||
Actual, for comparison | Present | >131.1 | December 2019 | - |
As of April 2018, the Sun showed signs of a reverse magnetic polarity sunspot appearing and beginning this solar cycle.[21] 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 suggested that a transition to cycle 25 was in process.[22] The first cycle 25 sunspot may have appeared in early April 2018[23] [24] or even December 2016.[22]
In November 2019, two reversed polarity sunspots appeared, possibly signaling the onset of cycle 25.[25] [26]
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.[27]
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.[28] A more recent supersynoptic map is available.[29]
The following table gives the number of days so far in cycle 25 against the number up to the same point in cycle 24, which have passed various thresholds for the numbers of sunspots.
Counts | ||||
≥100 | ||||
≥125 | ||||
≥150 | ||||
≥175 | ||||
≥200 | ||||
≥225 | ||||
≥250 | ||||
≥275 | ||||
≥300 | ||||
As at Aug 8, 2024, solar cycle 25 is averaging 35% more spots per day than solar cycle 24 at the same point in the cycle (Aug 8, 2013).
The strongest flares of Solar Cycle 25 (above M5.0 class) and related events
Class | Date | Sunspot region | Radio B. | SR Storm | GM Storm | ||
---|---|---|---|---|---|---|---|
X8.79 | 2024-05-14 | 3664 | R3 | - | Yes | ? | |
X6.37 | 2024-02-23 | 3590 | R3 | - | No | - | |
X5.89 | 2024-05-11 | 3664 | R3 | S2 | Yes | ? | |
X5.01 | 2023‑12‑31 | 3536 | R3 | S1 | Yes | - | |
X4.52 | 2024-05-06 | 3663 | R3 | - | Yes | G5 | |
X3.98 | 2024-05-10 | 3664 | R3 | S2 | Yes | G5 | |
X3.48 | 2024-05-15 | 3664 | R3 | - | Yes | ? | |
X3.38 | 2024-02-09 | 3575 | R3 | S2 | Yes | - | |
X2.99 | 2024-05-15 | 3685 | R3 | S1 | Yes | ? | |
X2.9 | 2024-05-27 | 3697 | R3 | - | Yes | - | |
X2.87 | 2023‑12‑14 | 3514 | R3 | S1 | Yes | G1 | |
X2.56 | 2024-02-16 | 3576 | R3 | S0 | Yes | - | |
X2.28 | 2023‑02‑17 | 3229 | R3 | - | Yes | - | |
X2.25 | 2022‑04‑20 | 2992 | R3 | - | Yes | - | |
X2.25 | 2024-05-09 | 3664 | R3 | S2 | Yes | G5 | |
X2.07 | 2023‑03‑03 | 3234 | R3 | - | Yes | - | |
X2.0 | 2024-07-16 | 3738 | R3 | - | Yes | ? | |
X1.98 | 2023‑01‑09 | 3184 | R3 | - | No | - | |
X1.9 | 2024-02-21 | 3590 | R3 | - | No | - | |
X1.72 | 2024-05-14 | 3664 | R3 | - | Yes | ? | |
X1.7 | 2024-02-22 | 3590 | R3 | - | No | - | |
X1.69 | 2024-05-02 | 3663 | R3 | - | Yes | - | |
X1.63 | 2023‑08‑05 | 3386 | R3 | S1 | Yes | - | |
X1.59 | 2021‑07‑03 | 2838 | R3 | - | Yes | - | |
X1.57 | 2024-07-29 | 3764 | R3 | - | No | - | |
X1.55 | 2024-06-10 | 3697 | R3 | - | Yes | ? | |
X1.54 | 2024-05-11 | 3664 | R3 | - | No | - | |
X1.51 | 2022‑05‑10 | 3006 | R3 | - | No | - | |
X1.51 | 2023‑08‑07 | 3386 | R3 | S1 | Yes | - | |
X1.45 | 2024-05-29 | 3697 | R3 | S0 | Yes | ? | |
X1.43 | 2024-06-01 | 3697 | R3 | - | No | - | |
X1.38 | 2022‑03‑30 | 2975 | R3 | S1 | Yes | G1 | |
X1.32 | 2024-05-05 | 3663 | R3 | - | No | - | |
X1.29 | 2024-05-05 | 3663 | R3 | - | No | - | |
X1.27 | 2023‑03‑29 | 3256 | R3 | - | Yes | - | |
X1.27 | 2024-07-14 | 3738 | R3 | - | No | - | |
X1.25 | 2024-05-14 | 3664 | R3 | - | Yes | ? | |
X1.22 | 2023‑01‑06 | 3182 | R3 | - | No | - | |
X1.18 | 2024-05-31 | 3697 | R3 | - | No | - | |
X1.17 | 2022‑04‑17 | 2994 | R3 | - | Yes | - | |
X1.16 | 2023‑02‑11 | 3217 | R3 | - | No | - | |
X1.13 | 2022‑04‑30 | 2994 | R3 | - | Yes | - | |
X1.13 | 2022‑05‑03 | 3006 | R3 | - | No | - | |
X1.12 | 2024-03-23 | 3614 | R3 | S2 | Yes | G4 | |
X1.12 | 2024-03-29 | 3615 | R3 | - | Yes | - | |
X1.12 | 2024-05-09 | 3664 | R3 | S2 | Yes | G5 | |
X1.11 | 2023‑06‑20 | 3341 | R3 | - | Yes | - | |
X1.08 | 2023‑07‑02 | 3354 | R3 | - | No | - | |
X1.08 | 2024-05-08 | 3663 | R3 | - | No | - | |
X1.06 | 2022‑10‑02 | 3110 | R3 | - | Yes | - | |
X1.06 | 2023‑01‑10 | 3186 | R3 | - | Yes | - | |
X1.04 | 2024-05-08 | 3663 | R3 | - | Yes | G5 | |
X1.03 | 2024-06-01 | 3697 | R3 | ? | ? | ? | |
X1.02 | 2024-05-08 | 3664 | R3 | - | No | - | |
X1.02 | 2024-05-12 | 3664 | R3 | - | No | - | |
X1.0 | 2021‑10‑28 | 2887 | R3 | S1 | Yes | - | |
M9.92 | 2024-07-28 | 3762 | R3 | - | No | - | |
M9.87 | 2024-05-08 | 3664 | R3 | - | Yes | G5 | |
M9.82 | 2023‑11‑28 | 3500 | R2 | - | Yes | G3 | |
M9.76 | 2024-03-28 | 3615 | R2 | - | No | - | |
M9.75 | 2024-06-08 | 3697 | R2 | S3 | Yes | ? | |
M9.67 | 2022‑03‑31 | 2975 | R2 | - | Yes | - | |
M9.66 | 2022‑04‑21 | 2993 | R2 | - | Yes | - | |
M9.62 | 2023‑05‑16 | 3310 | R2 | - | No | - | |
M9.56 | 2024-06-10 | 3697 | R2 | - | Yes | ? | |
M9.53 | 2023-04-30 | 3654 | R2 | - | No | - | |
M9.42 | 2024-03-30 | 3615 | R2 | - | Yes | - | |
M9.4 | 2024-07-30 | 3772 | R2 | - | Yes | - | |
M9.39 | 2024-03-30 | 3615 | R2 | - | Yes | - | |
M9.36 | 2024-06-23 | 3723 | R2 | - | No | - | |
M9.13 | 2024-05-04 | 3663 | R2 | - | No | - | |
M9.10 | 2024-05-04 | 3663 | R2 | - | No | - | |
M9.04 | 2024-02-10 | 3576 | R2 | S1 | Yes | - | |
M8.96 | 2023‑05‑20 | 3311 | R2 | - | No | - | |
M8.87 | 2024-05-11 | 3664 | R2 | S2 | Yes | - | |
M8.77 | 2022‑10‑02 | 3110 | R2 | - | Yes | G1 | |
M8.77 | 2024-07-29 | 3762 | R2 | - | Yes | ? | |
M8.72 | 2023‑09‑21 | 3435 | R2 | - | Yes | G2 | |
M8.69 | 2024-05-08 | 3664 | R2 | - | Yes | G5 | |
M8.67 | 2022‑08‑29 | 3088 | R2 | - | No | - | |
M8.62 | 2023‑02‑28 | 3234 | R2 | - | Yes | - | |
M8.42 | 2024-05-05 | 3663 | R2 | - | No | - | |
M8.29 | 2024-05-07 | 3663 | R2 | - | No | - | |
M8.24 | 2024-08-01 | 3772 | R2 | - | No | - | |
M8.23 | 2023‑09‑20 | 3435 | R2 | - | No | - | |
M7.92 | 2022‑09‑16 | 3098 | R2 | - | No | - | |
M7.92 | 2024-05-08 | 3664 | R2 | - | No | - | |
M7.88 | 2024-07-28 | 3766 | R2 | - | No | - | |
M7.79 | 2024-07-28 | 3762 | R2 | - | No | - | |
M7.75 | 2024-07-31 | 3772 | R2 | - | No | - | |
M7.48 | 2024-03-20 | 3615 | R2 | - | No | - | |
M7.47 | 2024-05-05 | 3663 | R2 | - | No | - | |
M7.43 | 2024-03-10 | 3599 | R2 | S0 | Yes | - | |
M7.43 | 2024-08-04 | 3768 | R2 | - | Yes | - | |
M7.35 | 2024-06-01 | 3697 | R2 | - | Yes | ? | |
M7.3 | 2024-08-04 | 3775 | R2 | - | No | - | |
M7.29 | 2022‑04‑20 | 2992 | R2 | - | Yes | - | |
M7.27 | 2023‑05‑03 | 3293 | R2 | - | No | - | |
M7.25 | 2024-05-17 | 3685 | R2 | ? | Yes | ? | |
M7.24 | 2022‑08‑26 | 3089 | R2 | - | Yes | - | |
M7.17 | 2024-05-08 | 3664 | R2 | - | No | - | |
M7.12 | 2023‑05‑01 | 3288 | R2 | - | No | - | |
M7.1 | 2024-03-28 | 3615 | R2 | - | No | - | |
M6.97 | 2023‑07‑12 | 3372 | R2 | - | No | - | |
M6.97 | 2023‑12‑15 | 3514 | R2 | - | Yes | G1 | |
M6.83 | 2023‑07‑11 | 3368 | R2 | - | No | - | |
M6.83 | 2024-01-29 | 3559 | R2 | S2 | Yes | - | |
M6.77 | 2024-03-18 | 3615 | R2 | - | No | - | |
M6.73 | 2022‑08‑28 | 3088 | R2 | - | Yes | - | |
M6.66 | 2024-05-13 | 3664 | R2 | S2 | Yes | ? | |
M6.57 | 2023‑05‑09 | 3296 | R2 | - | Yes | - | |
M6.51 | 2024-07-29 | 3772 | R2 | - | Yes | - | |
M6.5 | 2023‑05‑20 | 3311 | R2 | - | No | - | |
M6.5 | 2024-02-12 | 3576 | R2 | - | No | - | |
M6.39 | 2023‑02‑07 | 3213 | R2 | - | No | - | |
M6.36 | 2022‑12‑14 | 3165 | R2 | - | No | - | |
M6.35 | 2023‑02‑25 | 3229 | R2 | S1 | Yes | G3 | |
M6.2 | 2022‑09‑16 | 3098 | R2 | - | No | - | |
M6.14 | 2024-03-28 | 3615 | R2 | - | No | - | |
M6.12 | 2024-06-06 | 3697 | R2 | - | No | - | |
M6.07 | 2024-08-01 | 3772 | R2 | - | No | - | |
M6.04 | 2024-07-31 | 3772 | R2 | - | No | - | |
M6.03 | 2023‑01‑15 | 3191 | R2 | - | Yes | - | |
M6.01 | 2023‑09‑03 | 3413 | R2 | - | Yes | - | |
M5.97 | 2024-05-10 | 3664 | R2 | - | No | - | |
M5.86 | 2022‑10‑01 | 3110 | R2 | - | Yes | G1 | |
M5.86 | 2023‑07‑11 | 3372 | R2 | - | No | - | |
M5.84 | 2023‑12‑14 | 3514 | R2 | - | Yes | G1 | |
M5.8 | 2023‑03‑06 | 3243 | R2 | - | Yes | - | |
M5.76 | 2022‑05‑04 | 3004 | R2 | - | No | - | |
M5.76 | 2024-06-20 | 3719 | R2 | - | No | - | |
M5.74 | 2022‑12‑15 | 3165 | R2 | - | No | - | |
M5.73 | 2024-05-29 | 3691 | R2 | - | No | - | |
M5.72 | 2023‑07‑17 | 3363 | R2 | S2 | Yes | - | |
M5.68 | 2023‑05‑20 | 3311 | R2 | - | No | - | |
M5.67 | 2023‑01‑11 | 3184 | R2 | - | Yes | - | |
M5.54 | 2022‑05‑19 | 3014 | R2 | - | No | - | |
M5.51 | 2023‑08‑06 | 3386 | R2 | - | Yes | - | |
M5.5 | 2022‑01‑20 | 2929 | R2 | S1 | Yes | - | |
M5.49 | 2023‑12‑08 | 3511 | R2 | - | No | - | |
M5.47 | 2024-04-11 | 3639 | R2 | - | Yes | - | |
M5.46 | 2024-08-03 | 3775 | R2 | - | No | - | |
M5.41 | 2023‑03‑30 | 3256 | R2 | S0 | Yes | - | |
M5.39 | 2022‑08‑26 | 3089 | R2 | - | No | - | |
M5.39 | 2023‑05‑19 | 3311 | R2 | - | No | - | |
M5.39 | 2024-07-31 | 3772 | R2 | - | No | - | |
M5.35 | 2024-07-13 | 3738 | R2 | - | No | - | |
M5.34 | 2024-06-12 | 3697 | R2 | - | No | - | |
M5.32 | 2022‑05‑04 | 3006 | R2 | - | No | - | |
M5.27 | 2022‑03‑04 | 3234 | R2 | - | Yes | - | |
M5.25 | 2022‑11‑07 | 3141 | R2 | - | No | - | |
M5.2 | 2023‑05‑20 | 3311 | R2 | - | No | - | |
M5.18 | 2024-02-07 | 3575 | R2 | - | Yes | - | |
M5.18 | 2024-05-07 | 3663 | R2 | - | No | - | |
M5.15 | 2023‑01‑10 | 3186 | R2 | S0 | Yes | - | |
M5.12 | 2024-01-23 | 3559 | R2 | - | Yes | - | |
M5.09 | 2023‑02‑21 | 3234 | R2 | - | Yes | - | |
M5.08 | 2022‑08‑16 | 3078 | R2 | - | No | - | |
M5.07 | 2024-07-13 | 3738 | R2 | - | No | - | |
M5.05 | 2024-07-17 | 3743 | R2 | - | No | - | |
M5.04 | 2023‑03‑05 | 3243 | R2 | - | No | - | |
M5.02 | 2023‑05‑09 | 3296 | R2 | - | No | - |
Farside flares (above M5.0 class) observed by STIX[30]
Class | Date | Sunspot region | Class (seen from Earth) | |
---|---|---|---|---|
X14 | 2024-07-22 | 3738 | - | |
X12 | 2024-05-20 | 3664 | - | |
X9 | 2023-07-16 | 3368 | - | |
X9 | 2024-05-15 | 3664 | X3.48 | |
X9 | 2024-05-15 | 3664 | - | |
X7 | 2024-07-24 | 3738 | - | |
X6 | 2023-01-03 | 3182 | C4.06 | |
X6 | 2023-07-16 | 3368 | - | |
X6 | 2023-12-31 | 3536 | X5.01 | |
X6 | 2024-05-17 | 3664 | - | |
X5 | 2024-05-16 | 3664 | - | |
X4 | 2023-09-08 | 3413 | - | |
X4 | 2023-09-11 | 3413 | - | |
X4 | 2024-08-04 | 3738 | - | |
X3 | 2024-04-03 | ? | - | |
X3 | 2024-06-11 | 3697 | - | |
X3 | 2024-06-13 | 3697 | - | |
X3 | 2024-06-17 | 3697 | - | |
X2 | 2022-04-30 | 2994 | M1.99 | |
X2 | 2023-07-10 | 3354 | - | |
X2 | 2024-02-02 | ? | - | |
X2 | 2024-05-14 | 3664 | X1.25 | |
X1 | 2020-11-18 | 2786 | - | |
X1 | 2022-05-01 | 2994 | C1.9 | |
X1 | 2022-08-29 | 3088 | M8.68 | |
X1 | 2022-08-30 | 3088 | M1.7 | |
X1 | 2022-08-30 | 3088 | C7.18 | |
X1 | 2022-09-29 | 3112 | C5.76 | |
X1 | 2022-12-27 | 3180 | - | |
X1 | 2023-05-14 | 3310 | - | |
X1 | 2023-05-23 | 3323 | - | |
X1 | 2023-07-07 | 3354 | - | |
X1 | 2023-07-08 | 3354 | - | |
X1 | 2023-07-13 | 3360 | - | |
X1 | 2023-07-14 | 3372 | - | |
X1 | 2023-07-18 | 3368 | - | |
X1 | 2023-07-24 | ? | - | |
X1 | 2024-05-25 | 3664 | - | |
X1 | 2024-06-16 | 3697 | - | |
X1 | 2024-07-24 | 3738 | - | |
X1 | 2024-07-25 | 3738 | - | |
X1 | 2024-07-27 | 3738 | - | |
X1 | 2024-07-28 | 3738 | - | |
X1 | 2024-08-02 | 3738 | M1.33 | |
M9 | 2022-05-05 | 2994 | - | |
M9 | 2022-08-29 | 3088 | M4.71 | |
M9 | 2022-09-05 | 3088 | - | |
M9 | 2022-09-11 | 3089 | - | |
M9 | 2023-05-30 | 3323 | - | |
M9 | 2023-06-01 | 3310 | - | |
M9 | 2023-07-15 | ? | - | |
M9 | 2023-07-18 | 3368 | - | |
M9 | 2024-07-23 | 3738 | - | |
M8 | 2022-05-01 | 2994 | - | |
M8 | 2022-05-10 | 2994 | - | |
M8 | 2022-08-31 | 3088 | - | |
M8 | 2022-09-10 | 3089 | - | |
M8 | 2022-12-27 | 3180 | - | |
M8 | 2023-05-14 | 3310 | - | |
M8 | 2023-06-04 | ? | - | |
M8 | 2023-01-10 | 3549 | C9.64 | |
M8 | 2024-07-30 | 3738 | - | |
M7 | 2022-01-12 | ? | - | |
M7 | 2022-01-25 | ? | C3.79 | |
M7 | 2022-05-05 | 2994 | - | |
M7 | 2022-05-10 | 2994 | - | |
M7 | 2022-08-30 | 3088 | C7.57 | |
M7 | 2022-09-11 | 3089 | - | |
M7 | 2023-01-10 | 3190 | - | |
M7 | 2023-05-25 | 3323 | - | |
M7 | 2023-07-11 | 3354 | - | |
M7 | 2024-06-10 | ? | - | |
M7 | 2024-06-17 | 3697 | - | |
M6 | 2022-04-30 | 2994 | M4.82 | |
M6 | 2022-05-01 | 2994 | - | |
M6 | 2022-05-01 | 2994 | - | |
M6 | 2022-05-05 | 2994 | - | |
M6 | 2022-09-17 | 3098 | M2.61 | |
M6 | 2023-02-14 | 3229 | - | |
M6 | 2023-02-20 | 3234 | M4.43 | |
M6 | 2023-07-07 | 3354 | - | |
M6 | 2023-07-09 | 3354 | - | |
M6 | 2023-07-09 | 3354 | - | |
M6 | 2023-07-09 | 3354 | - | |
M6 | 2023-07-11 | 3372 | M1.17 | |
M6 | 2023-07-13 | 3360 | - | |
M6 | 2023-07-19 | 3363 | M3.81 | |
M6 | 2023-07-22 | 3363 | - | |
M6 | 2023-10-31 | 3477 | - | |
M6 | 2024-01-10 | 3549 | C7.01 | |
M6 | 2024-06-13 | 3697 | - | |
M6 | 2024-06-17 | 3697 | - | |
M6 | 2024-07-29 | 3738 | - | |
M5 | 2021-07-15 | ? | - | |
M5 | 2022-04-19 | 2992 | M3.71 | |
M5 | 2022-05-17 | 3014 | C9.91 | |
M5 | 2022-08-29 | 3088 | M2.58 | |
M5 | 2022-09-01 | 3088 | - | |
M5 | 2022-09-14 | 3089 | - | |
M5 | 2022-09-29 | 3112 | - | |
M5 | 2022-12-28 | 3180 | C6.09 | |
M5 | 2023-05-12 | 3310 | - | |
M5 | 2023-05-16 | 3310 | - | |
M5 | 2023-06-08 | ? | - | |
M5 | 2023-07-16 | ? | - | |
M5 | 2023-08-08 | 3387 | M3.67 | |
M5 | 2023-08-08 | 3387 | - | |
M5 | 2024-05-12 | 3685 | - | |
M5 | 2024-05-14 | 3685 | - | |
M5 | 2024-05-16 | 3664 | - | |
M5 | 2024-05-16 | 3664 | - | |
M5 | 2024-05-22 | 3664 | - | |
M5 | 2024-06-28 | ? | - | |
M5 | 2024-07-03 | ? | - | |
M5 | 2024-07-24 | 3738 | - |
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.[32] [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.[35]
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.[36]
The second X-class flare of the solar cycle erupted on 28 October, producing a CME and a S1 solar radiation storm.[37] Reports initially predicted that the CME could graze Earth,[37] however geomagnetic storms on 30–31 October only reached a moderate K index of 4.[38]
On 3 and 4 November, the K index reached 8−, equivalent to a G4 geomagnetic storm.[39] This was the most intense geomagnetic storm to hit Earth since September 2017.
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 up to that point.[46]
On 24 March, an intense geomagnetic storm hit Earth unexpectedly, reaching a level of G4 and producing auroras as far south as New Mexico. A minor CME from an M1 flare was predicted to hit the day earlier, but the timing and intensity were unexpected.[47] Later, on 23 and 24 April, more G4 storms hit Earth, on the former day being tied with several days in solar cycle 24 for the strongest storm since 2005.[48] Auroras were visible as far south as San Antonio, Texas.[49]
On 14 December, a solar flare measuring X2.87 was recorded from sunspot region 3514, making it the strongest solar flare of the cycle for just 17 days,[50] as on 31 December, a solar flare measuring X5.0 was recorded from sunspot 3536.[51]
On 9 February, region 3575 produced an X3.4 flare, the second strongest of the cycle up to that point, causing radiation levels to briefly exceed S2 over the following days.[52] On 12 February, after rotating to the far side of the Sun, the same region released a strong CME. As it was invisible from Earth, it was impossible to assess the flare's strength, but it nonetheless caused proton storm levels to briefly reach S2 again on February 12–13.
On 22 February, region 3590 produced a solar flare measuring X6.3.[53]
In May, the strongest solar storm in 20 years produced aurorae at far lower latitudes than usual. A few days later, on 14 May, region 3664 produced the strongest solar flare thus far of the solar cycle, measuring X8.7.[54] [55]
On 20 May 2024, an X12 solar flare – X-class are the strongest kind of solar flare – produced x-rays and gamma rays that hit Mars, while a coronal mass ejection launched a solar wind. [56]