Solar storms of different types are caused by disturbances on the Sun, most often from coronal mass ejections (CMEs) and solar flares from active regions, or, less often, from coronal holes. Minor to active solar storms (i.e. storming restricted to higher latitudes) may occur under elevated background solar wind conditions when the interplanetary magnetic field (IMF) orientation is southward, toward the Earth (which also leads to much stronger storming conditions from CME-related sources).
Background
Active stars produce disturbances in space weather and, if strong enough, in their own space climate. Science studies such phenomena with the field of heliophysics, which is an interdisciplinary combination of solar physics and planetary science.
In the Solar System, the Sun can produce intense geomagnetic and energetic particle storms capable of causing severe damage to technology. It can result in large scale power outages, disruption or blackouts of radio communications (including GPS), damage or destruction of submarine communications cables, and temporary to permanent disabling of satellites and other electronics. Intense solar storms may also be hazardous to high-latitude, high-altitude aviation and to human spaceflight. Geomagnetic storms are the cause of aurora. The most significant known solar storm, across the most parameters, occurred in September 1859 and is known as the "Carrington event". The damage from the most potent solar storms is capable of existentially threatening the stability of modern human civilization, although proper preparedness and mitigation can substantially reduce the hazards.
Proxy data from Earth, as well as analysis of stars similar to the Sun, suggest that the Sun may be also capable of producing so-called "superflares", which are as much as 1,000 times stronger than any flares in the historical record. Other research, like models of solar flares and statistics of extreme solar events reconstructed using cosmogenic isotope data in terrestrial archives, indicate otherwise. The discrepancy is not yet resolved and may be related to a biased statistic of the stellar population of solar analogs.
Coronal mass ejections and solar particle events
Events affecting Earth
Proxy evidence
This section contains a list of possible events that are indicated by indirect, or proxy data. The scientific value of such data remains unresolved.
- 12351–12350 BCE Probable Miyake event, which would be the largest known and twice the 774–775 event.
- 7176 BCE Found in beryllium-10 (and other isotopes) spike in ice cores and corroborated by tree rings. It unexpectedly appears to have occurred near a Solar minimum and was as strong as, or probably even slightly stronger than the famous 774–775 CE event.
- c. 5410 BCE
- 5259 BCE Found in beryllium-10 spike in ice cores and corroborated by tree rings. At least as strong as the 774–775 event.
- c. 660 BCE
- 774–775 CE This extreme solar proton event is the first identified Miyake event. It caused the largest and most rapid rise in carbon-14 levels ever recorded.
- 993–994 CE It caused a carbon-14 spike visible in tree rings which was used to date Viking archaeological remains in L'Anse aux Meadows in Newfoundland to 1021.
- 1052 CE found in carbon-14 spike
- 1279 CE found in carbon-14 spike
Direct measurements and/or visual observations
| Date | Event | Significance |
|---|---|---|
| Mar 1582 | Great magnetic storms of March 1582 | Prolonged severe-extreme geomagnetic storm produced aurora to 28.8° magnetic latitude (MLAT) and ≈33.0° invariant latitude (ILAT). |
| Feb 1730 | At least as intense as the 1989 event but less intense than the Carrington event | |
| Sep 1770 | ||
| Sep 1859 | Carrington Event | The most extreme storm ever documented by most measures; telegraph machines reportedly shocked operators and caused small fires; aurorae visible in tropical areas; first solidly established connection of flares to geomagnetic disturbances. Extreme storming directly preceded this event in late August. |
| Feb 1872 | Chapman–Silverman storm | Minimal Disturbance storm time index (Dst)* ≤ −834 nano-teslas (nT) |
| Nov 1882 | November 1882 geomagnetic storm | Comparable in size to the May 2024 storms. |
| Oct 1903 | Solar storm of Oct-Nov 1903 | An extreme storm, estimated at Dst −531 nT arose from a fast CME (mean ≈1500 km/s), occurred during the ascending phase of the minimum of the relatively weak solar cycle 14, which is the most significant storm on record in a solar minimum period. Aurora was conservatively observed to ≈44.1° ILAT, and widespread disruptions and overcharging of telegraph systems occurred. |
| Sep 1909 | Geomagnetic storm of September 1909 | Dst calculated to have reached −595 nT, comparable to the March 1989 event |
| May 1921 | May 1921 geomagnetic storm | Among most extreme known geomagnetic storms; farthest equatorward (lowest latitude) aurora ever documented; burned out fuses, electrical apparatus, and telephone station; caused fires at signal tower and telegraph station; total communications blackouts lasting several hours. A paper in 2019 estimates a peak Dst of −907±132 nT. |
| Jan 1938 | January 1938 geomagnetic storm, or the Fátima storm | A series of intense geomagnetic storms during the month of January 1938. Most powerful (25-26) comparible in intensity to the Oct 2024 storm, caused auroras across Europe. |
| Mar 1940 | March 1940 superstorm | Triggered by an X35±1 solar flare. Caused significant interference to United States communication systems. |
| Sep 1941 | ||
| Mar 1946 | Geomagnetic storm of March 1946 | Est. Dstm of −512 nT |
| Feb 1956 | ||
| Sep 1957 | Geomagnetic storm of September 1957 | |
| Feb 1958 | Geomagnetic storm of February 1958 | |
| Jul 1959 | Geomagnetic storm of July 1959 | |
| May 1967 | Blackout of polar surveillance radars during Cold War led U.S. military to scramble for nuclear war until solar origin confirmed | |
| Oct 1968 | ||
| Aug 1972 | August 1972 solar storms | Fastest CME transit time recorded; most extreme solar particle event (SPE) by some measures and the most hazardous to human spaceflight during the Space Age; severe technological disruptions, caused accidental detonation of numerous magnetic-influence sea mines |
| Mar 1989 | March 1989 geomagnetic storm | Most extreme storm of the Space Age by several measures. Outed power grid of province of Quebec. Caused interference to United States power grid. 2024 study estimated Dstm of −750 nT. |
| Aug 1989 | ||
| Nov 1991 | Geomagnetic storm of November 1991 | An intense solar storm with about half the energy output of the March 1989 storm. Aurorae were visible in the US as far south as Texas |
| Apr 2000 | ||
| Jul 2000 | Bastille Day solar storm | Caused by an X8-class solar flare aimed directly at Earth |
| Apr 2001 | A solar flare from a sunspot region associated with this activity and preceding this period produced the then largest flare detected during the Space Age at about X20 (the first event to saturate spaceborne monitoring instruments, this was exceeded in 2003) but was directed away from Earth. | |
| Nov 2001 | Geomagnetic storm of November 2001 | A fast-moving CME triggered vivid aurorae as far south as Texas, California, and Florida |
| Oct 2003 | 2003 Halloween solar storms | Among top few most intense storms of the Space Age; aurora visible as far south as Texas and the Mediterranean countries of Europe. A solar flare with x-ray flux estimated to be around X45 occurred from an associated active region on 4 November but was directed away from Earth. |
| Nov 2003 | Solar storms of November 2003 | 2021 study estimated Dstm of −533 nT. 2024 study estimated Dst of −490 nT |
| Jan 2005 | The most intense solar flare in 15 years with sunspot 720 erupting, 5 times from January 15 to 20. | |
| Mar 2015 | St. Patrick's Day storm | Largest geomagnetic storm of solar cycle 24, driven by interplanetary magnetic field (IMF) variations |
| Sep 2017 | Triggered by an X13 class solar flare | |
| Feb 2022 | A mild solar particle and geomagnetic storm of otherwise little consequence led to the premature reentry and destruction of 40 SpaceX Starlink satellites launched February 3, 2022 due to increased atmospheric drag. | |
| 30 April – 12 May 2024 | May 2024 solar storms | X1.2(X1.3)-class flares and X4.5-class flare. The flares with a magnitude of 6–7 occurred between 30 April and 4 May 2024. On 5 May the strength of the solar storm reached 5 points, which is considered strong according to the K-index. The rapidly growing sunspot AR3663 became the most active spot of the solar cycle 25. On 5 May alone, it emitted two X-class (strongest) flares and six M-class (medium) flares. Each of these flares resulted in a short-term but profound disconnection of the Earth's radio signal, resulting in signal loss at frequencies below 30 megahertz (MHz). An extreme (G5) geomagnetic storm alert was issued by the National Oceanic and Atmospheric Administration (NOAA) – the first in almost 20 years. The final storms reaching the highest level of NOAA's G-scale before solar cycle 25 occurred in 2005 in May, August, and September, respectively. With a NOAA rating of G5, an estimated peak Dst of −412 nT, and aurorae seen at far lower latitudes than usual in both hemispheres, this geomagnetic storm was the most powerful to affect Earth since November 2003. A later study estimates a Dst peak of −518 nT, meaning the strongest storm since 1989 and the second strongest since 1921. |
| Oct 2024 | October 2024 solar storm | Triggered by an X1.8 solar flare that produced a relatively fast CME. The storm reached a peak Dst of −341 nT. Auroras seen as far south as Cuba. |
| Nov 2025 | November 2025 solar storm | Auroras seen as far south as Central Mexico. |
Events not affecting Earth
The above events affected Earth (and its vicinity, known as the magnetosphere), whereas the following events were directed elsewhere in the Solar System and were detected by monitoring spacecraft or other means.
| Date(s) | Event | Significance |
|---|---|---|
| 23 July 2012 | July 2012 solar storm | Ultrafast CME directed away from Earth with characteristics that may have made it a Carrington-class storm |
| 1 Sep 2014 | Caused a fast CME and a proton event. | |
| 23 July 2017 | 5 years after the 2012 CME. | |
| 15 Feb 2022 | ||
| 21 Oct 2025 |
Soft X-ray solar flares
Solar flares are intense localized eruptions of electromagnetic radiation in the Sun's atmosphere. They are often classified based on the peak flux of soft X-rays (SXR) measured by the GOES spacecraft in geosynchronous orbit (see Solar flare § Soft X-ray classification).
The following table lists the largest flares in this respect since June 1996, the beginning of solar cycle 23.
| No. | SXR Class | Date | Solar cycle | Active region | Time (UTC) | Notes | ||
|---|---|---|---|---|---|---|---|---|
| Start | Max | End | ||||||
| 1 | >X28+ | 2003-11-04 | 23 | 10486 | 19:29 | 19:53 | 20:06 | Associated with the 2003 Halloween solar storms |
| 2 | X20 | 2001-04-02 | 23 | 9393 | 21:32 | 21:51 | 22:03 | |
| 3 | X17.2 | 2003-10-28 | 23 | 10486 | 09:51 | 11:10 | 11:24 | Associated with the 2003 Halloween solar storms |
| 4 | X17 | 2005-09-07 | 23 | 10808 | 17:17 | 17:40 | 18:03 | |
| 5 | X14.4 | 2001-04-15 | 23 | 9415 | 13:19 | 13:50 | 13:55 | |
| 6 | X10 | 2003-10-29 | 23 | 10486 | 20:37 | 20:49 | 21:01 | Associated with the 2003 Halloween solar storms |
| 7 | X9.4 | 1997-11-06 | 23 | 8100 | 11:49 | 11:55 | 12:01 | |
| 8 | X9.3 | 2017-09-06 | 24 | 12673 | 11:53 | 12:02 | 12:10 | |
| 9 | X9.0 | 2006-12-05 | 23 | 10930 | 10:18 | 10:35 | 10:45 | |
| 10 | X8.3 | 2003-11-02 | 23 | 10486 | 17:03 | 17:25 | 17:39 | Associated with the 2003 Halloween solar storms |
See also
- Active region
- Coronal mass ejection
- Earth's magnetic field
- Gamma-ray burst and hypernova
- Health threat from cosmic rays
- Heliosphere
- Miyake event
- Solar cycle
- Space physics
- Space Weather Prediction Center (SWPC)
Further reading
- Cliver, E.W.; L. Svalgaard (2004). "The 1859 Solar–Terrestrial Disturbance and the Current Limits of Extreme Space Weather Activity" (PDF). Solar Physics. 224 (1–2): 407–22. Bibcode:2004SoPh..224..407C. doi:10.1007/s11207-005-4980-z. S2CID 120093108. Archived from the original (PDF) on 2011-08-11. Retrieved 2014-05-07.
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