Solar Orbiter Traces Solar Wind Switchbacks to the Sun's Surface
Particles inside a giant magnetic switchback point to reconnection in hot loops at the Sun's surface, Solar Orbiter data show, aiding space weather models.
ESA’s Solar Orbiter has traced a magnetic switchback, an S-shaped kink in the solar wind’s magnetic field, back to its likely birthplace at the surface of the Sun. The study, led by Jesse Coburn of CNRS/LPP, is published in Nature Astronomy, and ESA reported the result on October 8, 2026. Solar Orbiter had already confirmed the S shape of these structures in 2022.
The spacecraft flew through a very large switchback while it was roughly halfway between Earth and the Sun. Its Solar Wind Analyser sampled the particles inside and found a mix of charged oxygen and carbon that can only form in hot magnetic loops at the Sun’s surface. That chemical fingerprint points to “interchange reconnection”, in which open magnetic field lines that stream out into space reconnect with closed loops anchored at the surface.
Two explanations had competed: switchbacks born at the Sun, or switchbacks created later by waves and turbulence in the flowing wind. The new data suggest both play a part. The switchback starts at the surface, then waves and turbulence appear to govern it after it leaves. This is one well-measured event, so it shows a mechanism that works, not yet how common it is. Learning how the solar wind and its magnetic structures form helps explain the space weather that drives solar storms at Earth. Our Solar System guide and guide to stars cover the Sun in more depth.
What to watch next: further passes through switchbacks will test whether the same particle signature shows up every time.
Primary source
This summary is based on ESA and the peer-reviewed paper. Read the original for full details, data and caveats.
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