Researchers from the Max Planck Institute for Solar System Research (MPS) and the University of Colorado have found new evidence that the Sun’s largest historical sunspots could, in rare cases, produce superflares.
The study, led by Natalie Krivova and published on 10 September 2026 in Philosophical Transactions of the Royal Society A (arXiv:2603.09474), focuses on empirical upper limits for solar flare energies.
The team analyzed data from NASA’s Solar Dynamics Observatory (SDO) on more than 300 of the strongest flares observed between 2010 and 2016. They related flare energy (via flare-ribbon areas as a proxy for magnetic reconnection) to the size of the associated active regions.
They then extrapolated the upper- envelope statistical relations (focusing on the extreme tail of the distribution) to historical sunspot records, which have been systematically tracked for centuries.
The standout case is the Great Sunspot of April 1947 (Active Region 14886), one of the largest on record. It covered roughly 0.6% of the visible solar disk (maximum corrected area ~6,100- 6,132 millionths of the solar hemisphere), with a diameter about 40 times that of Earth. No superflare occurred then.
This builds on a 2024 MPS- led study (published in Science) of ~56,450 Sun- like stars observed by Kepler.
That work found superflares occur roughly once per century on such stars, far more frequently than earlier estimates.
The new results indicate the Sun is, in principle, “superflare- capable” because it can form sufficiently large and complex active regions/sunspots. Extreme events would still be rare, and the relationship between the largest flares, coronal mass ejections, and extreme solar particle events (inferred from cosmogenic isotopes) is not one- to- one.
No superflare has been directly observed on the modern Sun, and whether one has ever occurred remains an open question. The work strengthens the case that such events are physically plausible on the basis of observed solar structures and stellar statistics, with potential relevance for extreme space weather risks to technology and infrastructure.
The Carrington Event (also called the Carrington Storm or solar storm of 1859) remains the most intense geomagnetic storm in recorded history. It peaked on 1- 2 September 1859 during solar cycle 10 and is named after British astronomer Richard Carrington, who made the first observation of a solar flare associated with it.
The flare originated in a large sunspot group. Modern estimates of its maximum corrected area range from roughly 2,300- 3,500 millionths of the solar hemisphere (msh), with some reconstructions adopting ~3,100 msh as a conservative value. This places it among the larger historical active regions, though smaller than the record 1947 Great Sunspot (~6,100 msh).
Late August 1859: A large, complex sunspot group was visible on the Sun. Auroral activity and magnetic disturbances began around 28- 29 August, indicating earlier coronal mass ejections (CMEs) from the same region.
1 September 1859, ~11:18 GMT: Richard Carrington (and independently Richard Hodgson) observed a brilliant white- light flare lasting about 5 minutes while sketching the sunspot group. Carrington described “two patches of intensely bright and white light.” Magnetometers simultaneously recorded a “crochet” (solar flare effect) caused by enhanced ionospheric ionization.
~17- 18 hours later (early 2 September): A fast CME arrived at Earth, triggering the main geomagnetic storm. The short transit time implies an unusually high speed (roughly 2,000 and more km/s).
The flare originated in a large sunspot group. Modern estimates of its maximum corrected area range from roughly 2,300- 3,500 millionths of the solar hemisphere (msh), with some reconstructions adopting ~3,100 msh as a conservative value. This places it among the larger historical active regions, though smaller than the record 1947 Great Sunspot (~6,100 msh).
Flare magnitude estimates (modern GOES soft X- ray scale, revised) typically fall in the range X45- X146, with many studies centering around ~X45. Bolometric (total radiated) energy estimates are on the order of a few erg, with some approaching ∼erg depending on conversion factors from soft X- ray class. Recent analyses of Carrington’s original drawings have suggested even higher values in some scenarios (e.g., ~X80 range), though uncertainties remain large.
Auroras: Extremely bright and widespread. They were visible at unusually low geomagnetic latitudes, down to ~18- 25° (Caribbean, Central America, Hawaii, Colombia, and possibly lower). People in the northeastern United States could read newspapers by auroral light; gold miners in the Rocky Mountains woke and began preparing breakfast, thinking dawn had arrived. Displays lasted many hours and included red, green, and other colors.
Geomagnetic storm intensity: Estimates of the storm’s strength (Dst index) range widely from about -800 nT to as low as -1,750 nT or lower in early analyses (based partly on the Colaba, India magnetogram). More recent re- evaluations often place it around -900 nT or somewhat stronger, still far exceeding modern extreme events (e.g., March 1989 Quebec storm ~–589 nT). Rapid field changes induced strong geoelectric fields.
Telegraph systems: Widespread disruption across Europe and North America. Operators reported electric shocks, sparks, and fires at stations. In some cases (notably the Boston- Portland line), operators disconnected batteries and continued transmitting messages using only the currents induced by the storm, the so- called “auroral current” or “celestial power.”
The Carrington Event is the benchmark for extreme space weather. A comparable event today could severely disrupt satellites, GPS, power grids, and communications, with potential economic costs in the hundreds of billions to trillions of dollars (depending on the region and duration of outages).
It is often treated as a “1- in- 100 to 1- in-500 year” (or rarer) event, though related extreme solar particle events inferred from cosmogenic isotopes (e.g., AD 774/775) indicate that even stronger particle events have occurred over millennia.
In the context of the recent Krivova et al. (2026) study, the Carrington active region’s size yields estimated flare energies consistent with independent historical reconstructions (typically ~ erg under upper envelope scalings, with higher outliers possible), reinforcing that it ranks among the most energetic flares in the observational record while remaining below true stellar superflare energies (erg).
The event also marks the birth of solar– terrestrial physics: Carrington cautiously noted the coincidence between the flare and the subsequent magnetic storm, establishing the first clear observational link.
_____________________________________________________________________________________
Here are the confirmed publication details for the two related papers from the Max Planck Institute for Solar System Research (MPS) and collaborators, both appearing in the same 2026 issue of Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences:
Natalie Krivova et al., “Empirical flare energy limits for the largest historical sunspots”
This is the main empirical study discussed previously. It uses SDO/RibbonDB flare data (2010- 2016) to derive upper- envelope scaling relations between active-region/sunspot size and flare energy, then extrapolates to the largest historical sunspots (especially the April 1947 Great Sunspot).
It concludes that such regions could, in rare extreme cases, reach bolometric energies of a few erg, overlapping the lower end of the stellar superflare regime.
Published: Philosophical Transactions of the Royal Society A Mathematical, Physical and Engineering Sciences (2026)
Valeriy Vasilyev et al., “Linking solar magnetism, extreme solar particle events and stellar superflares”
This is a complementary review/synthesis paper. It discusses the connections (and differences) between extreme solar particle events (ESPEs, inferred from cosmogenic isotopes), solar magnetic activity, and stellar superflares observed on Sun- like stars. It notes that while both ESPEs and superflares involve extreme magnetic energy release, the relationship is not one- to- one.
Published: Philosophical Transactions of the Royal Society A Mathematical, Physical and Engineering Sciences (2026)
These two papers were highlighted together in the Max Planck Society press release of 10 September 2026 (“Sonne: Neuer Hinweis auf Superflares” / “Sun: New Evidence of Superflares”).
The Krivova paper provides the new empirical evidence that the Sun’s largest recorded sunspots have the potential to power superflare -level energies, while the Vasilyev paper places that finding in the broader context of solar- stellar comparisons and extreme particle events.
You must be logged in to post a comment.