The Solar Orbiter probe, led by the European Space Agency (ESA), has traced back to the Sun’s surface the origin of a ‘switchback’, an S-shaped kink in the magnetic field of the solar wind. In 2022 the mission had already confirmed the shape of these structures, which scientists had predicted but never directly observed.
The Solar Wind Analyser instrument sampled the plasma in the switchback when the probe was roughly halfway between the Earth and the Sun. The mixture of charged oxygen and carbon particles it found can only form in hot magnetic loops at the solar surface, which points to a process known as ‘interchange reconnection’.
The lead author, Jesse Coburn of France’s CNRS, described this mixture as the ‘smoking gun’ for the phenomenon. Co-author Stephanie Yardley, of Northumbria University in the UK, believes that waves and turbulence also play a part, but at a later stage in the life of these structures.
The study, published in the journal Nature Astronomy, helps explain how the Sun heats its atmosphere and accelerates the solar wind. According to Daniel Müller, ESA project scientist, a better understanding of solar dynamics will help protect space infrastructure from extreme solar storms.
