In January 2026, researchers published a breakthrough study in Astronomy & Astrophysics that finally identifies the "central engine" of solar flares. Using high-resolution data from the ESA’s Solar Orbiter, scientists observed that these massive eruptions are not single, monolithic explosions, but are instead powered by a "magnetic avalanche."
This discovery confirms a long-theorized model of how our star releases stored energy, providing the clearest insight yet into the mechanics that drive space weather.
The Discovery: A Chain Reaction in the Corona
On September 30, 2024, the Solar Orbiter was positioned just 43 million kilometers from the Sun—roughly one-third the distance between the Earth and the Sun. During this close approach, its instruments captured an M7.7-class solar flare with unprecedented detail, recording changes every two seconds.
The data revealed that the flare was preceded by a series of small, rapid "micro-reconnections." Like a small patch of snow sliding down a mountain, these tiny magnetic disturbances destabilized neighboring regions, triggering a cascading avalanche of energy release.
Key Characteristics of the Magnetic Avalanche
Scale: The imager resolved structures as small as 200 kilometers across.
Speed: New magnetic strands appeared and broke every 2 seconds or less.
Energy Shift: Particles were accelerated to between 40% and 50% the speed of light ($120,000 \text{ to } 150,000 \text{ km/s}$).
Visual Marker: Bright "ribbon-like" features and "raining plasma blobs" served as signatures of the energy being dumped into the solar atmosphere.
How the "Engine" Works
The "hidden engine" is a process called magnetic reconnection. In the Sun’s plasma-filled atmosphere, magnetic field lines become twisted and tangled like frayed ropes. When these lines of opposite polarity are forced together, they "snap" and reconfigure, releasing massive amounts of stored potential energy.
| Phase | Observational Detail |
| The Build-up | A dark, arch-like filament of twisted plasma becomes connected to a brightening "cross-shaped" magnetic structure. |
| The Trigger | Small-scale reconnection events begin at the "foot" of the flare, occurring rapidly and spreading across the region. |
| The Avalanche | The filament becomes unstable, disconnects from one side, and "unrolls" violently at speeds up to 400 km/s. |
| The Peak | A massive surge in X-ray and ultraviolet emission occurs as the cascade reaches its crescendo, launching a flare. |
| The Aftermath | "Coronal rain" (blobs of cooling plasma) continues to fall back to the surface even after the main explosion ends. |
Why It Matters: Predicting Space Weather
Understanding that flares are "avalanches" changes how we monitor the Sun. Previously, flares were often viewed as sudden, unpredictable "pops." Now, scientists have identified precursor signatures—the micro-reconnections and initial plasma "rain"—that occur up to 40 minutes before the main eruption.
This knowledge could lead to:
Earlier Warnings: Recognizing the "snowball effect" of magnetic disturbances before they become full-scale flares.
Infrastructure Protection: Better preparation for geomagnetic storms that can disable satellites, GPS, and power grids on Earth.
Stellar Physics: Applying the "avalanche model" to other stars in the galaxy to understand how they interact with their own planets.
"Solar Orbiter’s observations unveil the central engine of a flare and emphasize the crucial role of an avalanche-like magnetic energy release mechanism at work."
— Dr. Miho Janvier, Solar Orbiter Project Scientist