The chaotic origins of solar flares have been unveiled in new observations by ESA's Solar Orbiter, offering a rare and detailed look at the early warning signs of these powerful solar events. Solar flares, far from being sudden explosions, begin with small disturbances that can quickly spiral out of control, leading to massive releases of energy. This new data reveals that these flares can grow from tiny disruptions, with the Sun's atmosphere turning into a chaotic scene filled with glowing plasma blobs that fall back toward the surface even after the main explosion has passed. The event looked more like a chain reaction that fed on itself, rather than a single outburst.
Solar flares matter on Earth because they can shake Earth's magnetic field, disrupt radio signals, and interfere with satellites. The strongest flares can cause significant disruptions, which is why scientists closely monitor these eruptions. While researchers had long understood the basics of solar flares, they lacked the details of how these events unfold. The speed and scale of the energy release were particularly hard to explain.
On September 30, 2024, during a close pass by the Sun, the Solar Orbiter spacecraft captured one of the most detailed views of a large solar flare ever recorded. Four instruments worked together, tracking changes every two seconds in some regions, revealing how the flare slowly built up over about 40 minutes before reaching its peak. The study's lead author, Pradeep Chitta from the Max Planck Institute for Solar System Research, expressed the luck of witnessing the precursor events in such detail.
The spacecraft observed a dark, arch-shaped filament made of twisted magnetic fields and plasma, along with a cross-shaped pattern of magnetic lines that slowly grew brighter. Every couple of seconds, new magnetic strands appeared, twisting tighter like a rope under strain. The system then tipped, with the strands breaking and reconnecting, releasing more and more energy. The images showed sudden flashes growing brighter as the process sped up.
At 11:29 p.m. Universal Time, one brightening stood out, with the dark filament tearing loose on one side, shooting outward, and unraveling at high speed. Bright sparks lit up along its length as the main flare erupted around 11:47 p.m. Chitta noted that these minutes before the flare are crucial, and Solar Orbiter provided a window into the foot of the flare where the avalanche process began.
The flare unfolded as a cascade of interacting reconnection events, with each one adding fuel to the next, pushing the system toward a full-scale outburst. The observations also revealed what happened to the energy once it was released, with fast particles slamming into the Sun's atmosphere, heating the plasma and sending bright streams racing downward. During the peak of the flare, particles were accelerated to 40–50 percent of the speed of light.
This kind of speed matters because particles that escape the Sun can pose radiation risks to satellites, astronauts, and technology on Earth. The streams of 'raining plasma' got stronger and stronger as the flare progressed, and even after the flare subsided, the rain continued for some time. This is the first time such observations have been made at this level of spatial and temporal detail in the solar corona.
After the storm passed, the scene began to calm, with the bright, cross-shaped magnetic pattern relaxing, the plasma cooling, and particle emissions dropping back toward normal levels. The energy involved still surprised the researchers, and the findings suggest that avalanche-style energy release may be a common feature of flares on many stars.
