Solar flares are powerful bursts of radiation from the sun’s surface, which can wreak havoc on Earth’s power grids, damage orbiting satellites, and pose serious radiation risks to astronauts. Yet despite decades of study, the processes that trigger these eruptions remain poorly understood.
In a new preprint on arXiv, a team led by Louis Seyfritz at the New Jersey Institute of Technology has captured rare observations of a large flare in the hours before it erupted, offering new clues about what sets these events in motion.
A rare common target
On October 3, 2024, a region of intense magnetic activity on the sun unleashed an X9.0-class flare—among the most powerful category of solar flare. In a rare and fortunate convergence, several different space telescopes had already been trained on that same region, anticipating a possible eruption after the same area had produced a strong flare just days earlier. The result was a detailed dataset capturing the flare’s behavior from hours before it occurred.
In their study, Seyfritz’s team analyzed three properties of this light: how turbulent the plasma was, whether it was moving towards or away from the sun, and how bright it appeared. By tracking how these quantities changed over time, and applying wavelet analysis to identify repeating patterns, the team was able to piece together a picture of conditions in the lead-up to the flare.
Fluctuations and intensifying brightness
The data revealed two sets of rhythmic fluctuations playing out during the pre-flare phase: one cycling roughly every 7–10 minutes, and another with a longer period of around 18–21 minutes. These oscillations appeared concentrated near the boundary between regions of opposing magnetic polarity on the sun’s surface.
Alongside these fluctuations, the team also found a steady, gradual increase in all three light properties beginning around three hours before the flare, concentrated in the same area. Roughly 15–20 minutes before the flare began, this steady rise gave way to an abrupt intensification, with plasma turbulence surging and material beginning to rush away from the sun.
Pre-flare properties
Together, the team’s findings paint a coherent picture of how the pre-flare phase unfolds. The gradual rise over three hours points to a slow, progressive destabilization of the sun’s magnetic field, possibly driven by the buildup of a twisted magnetic structure called a “flux rope.”
The two oscillation periods may hint at distinct physical processes occurring simultaneously within the plasma. And the sharp transition seen in the final minutes before the flare suggests a sudden shift to explosive magnetic reconnection: the process that ultimately powers the eruption.
For now, it remains unclear whether similar warning signs may appear before other solar flares. However, Seyfritz’s team hope that their findings could represent a promising step towards more advanced forecasting techniques—helping astronomers to better understand how these dramatic events unfold, and how we can better protect vital infrastructures both on Earth and in space.
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Publication details
Louis Seyfritz et al, Investigating Pre-flare Signatures in Spectroscopic Observations of an X9-class Solar Flare, arXiv (2026). DOI: 10.48550/arxiv.2605.07889
Journal information:
arXiv
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Rare observations reveal an X9 solar flare before it erupts (2026, May 27)
retrieved 27 May 2026
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