ESA’s Solar Orbiter has revealed the Sun’s dual particle engines — solar flares and coronal mass ejections. By tracing 300 events, scientists solved key mysteries of solar radiation, improving space weather forecasts to protect astronauts.
For decades, scientists knew the Sun could hurl bursts of high-speed particles into space, but the details of their origins remained unclear. Now, thanks to the European Space Agency’s Solar Orbiter mission, the mystery is being solved.
Between November 2020 and December 2022, Solar Orbiter recorded over 300 bursts of Solar Energetic Electrons (SEEs) — subatomic particles accelerated to near light speed. For the first time, researchers have linked them directly to their sources on the Sun.
The study, published in Astronomy & Astrophysics, shows that the Sun has two distinct “particle engines”:
Solar flares: Quick, explosive bursts that fire electrons suddenly into space.
Coronal mass ejections (CMEs): Huge eruptions of hot gas that send broader waves of electons more gradually.
This discovery helps explain why energetic particles sometimes appear delayed after solar eruptions. As ESA research fellow Laura Rodríguez-García explains, electrons can be scattered and slowed by turbulence in the solar wind, meaning they don’t always reach detectors right away.
Lead author Alexander Warmuth of the Leibniz Institute for Astrophysics says the unique advantage of Solar Orbiter is its ability to measure particles close to the Sun, capturing them in a more “pristine” state. This allowed scientists to pinpoint both the time and place of their release.
Understanding these two particle pathways is crucial for space weather forecasting. Events linked to CMEs carry more high-energy particles, posing a greater threat to satellites, spacecraft, and astronauts. Better knowledge means better protection for future missions.
ESA’s Vigil mission (launching 2031) and Smile mission (launching 2026) will build on this progress, helping forecast hazardous solar storms and study how Earth’s magnetic field shields us.
“Thanks to Solar Orbiter, we now understand the Sun’s particle engines like never before,” said ESA project scientist Daniel Müller. “This knowledge will help keep spacecraft and astronauts safe in the years to come.”