Scientists using the European Space Agency's Solar Orbiter have traced the origin of magnetic switchbacks in the solar wind to the Sun's surface. Switchbacks are sudden S-shaped kinks in the magnetic field, and a recent close pass through one allowed the spacecraft's Solar Wind Analyser to sample particles with distinctive signatures. Those particles could only have formed within hot magnetic loops at the solar surface, providing a direct link to their source.
The measurements support a formation process called interchange reconnection, where open magnetic field lines stretching into space interact with closed loops that bend back toward the Sun. When these lines meet, they can snap open and release trapped plasma. The other leading theory, involving waves and turbulence, also shows signs in the data, but researchers say those effects likely take over only after the switchback has already left the Sun.
Understanding how switchbacks form is more than a curiosity. The solar wind ties Earth to the Sun, and knowing how it is accelerated helps scientists predict solar storms and their potential impact on space-based infrastructure. As ESA project scientist Daniel Müller put it, the more we learn about the Sun's dynamics, the better we can prepare for extreme space weather events.