A paper published in the Journal of Geophysical Research suggests we may be overdue for a super solar flare. The last such event occurred on 4 November 2003.
A super flare is 10 times stronger than an X-flare, which occurs more often. Solar flares are powerful explosions on the sun that pepper satellites with energetic particles and trigger great geomagnetic storms.
Solar flares are classified by lettered categories: A, B, C, M, X and S, based on their peak soft X-ray flux. Each category represents a ten-fold increase in energy, with S being the most intense and A the weakest.
During the current solar cycle (Solar Cycle 26) Earth has not yet experienced an S-flare. According to researchers led by V.M. Velasco Herrera of the National Autonomous University of Mexico, that is somewhat unusual. The team looked at 50 years of data from Earth-orbiting satellites. Among 95 627 solar flares, they found 37 Earth-directed S-flares. Every solar cycle since the 1970s has produced at least one.
There are some clues to when the next S-flare might happen. In the 50-year dataset, the researchers found two underlying rhythms: 1.7 years and 7 years, both linked to magneto-Rossby waves inside the sun.
Magnetic Rossby waves are large-scale, slow-moving oscillations in rotating conducting fluids (plasmas) where both Coriolis and Lorentz forces act, commonly found in astrophysical bodies like the Sun's interior and planetary cores.
They represent a magnetic modification of classic hydrodynamic Rossby waves, splitting them into distinct fast and slow modes. These waves occur due to a gradient in planetary vorticity (Coriolis force) combined with the influence of magnetic fields (Lorentz force).
In the Sun, they contribute to organising magnetic fields into "preferred longitudes" and activity nests, which are linked to the solar dynamo and magnetic field cycles. When both rhythms swing into their positive phase at the same time, the probability of an S-flare spikes.
According to those rhythms, a high-risk S-flare window exists from mid-2025 through mid-2026. The next high-risk window opens in early 2027 and lasts about six months.
