Solar Dynamics Observatory imagery from February 28, 2022, overlaid with modelled magnetic connections for Solar Orbiter’s encounter. The coloured markers are model estimates, not direct photographs of field lines. Credit: J. T. Coburn et al., Nature Astronomy (2026), Fig. 1, CC BY 4.0. Reproduced without alteration.
Particles caught inside a sharp bend in the solar wind have given researchers a way to investigate where that magnetic disturbance began. In an October 8, 2026 announcement, the European Space Agency described how Solar Orbiter used the composition of a magnetic “switchback” to connect it with conditions in the Sun’s atmosphere.
The newly published analysis examines measurements collected on March 2, 2022, when the spacecraft was about 55 percent of Earth’s distance from the Sun. That distinction matters: the October development is the scientific interpretation of an earlier encounter.
A sample with a history
The Nature Astronomy study, led by Jesse T. Coburn, identifies unusual oxygen and carbon charge-state ratios, together with relatively little helium. The combination points to plasma that had occupied hot, closed magnetic loops in the corona, the Sun’s outer atmosphere.
The proposed escape route is interchange reconnection. A closed loop interacts with magnetic field extending outward into space, changes its connections, and releases previously confined material. The researchers combined particle measurements with solar observations and magnetic-field modelling to investigate this route.
The paper also describes an important limit: the models guide the search for the source region, rather than pinpointing an exact birthplace. The composition constrains the possible origin to structures associated with a coronal hole or its boundary.
Different instruments answer different questions
Switchbacks have a long observational history. ESA’s September 2022 account traces sudden, temporary field reversals back to the Helios probes in the 1970s. Parker Solar Probe later found them especially common near the Sun.
A spacecraft passing through one samples the field at its own location. Reconstructing a whole structure from that single moving viewpoint can be difficult. Solar Orbiter’s Metis coronagraph supplied a complementary view on March 25, 2022, capturing an S-shaped feature in coronal plasma that researchers interpreted as a switchback.
That imaging result and the newly analysed particle encounter are separate observations. Together they illustrate why the mission combines instruments that look at the Sun with instruments that sample its surroundings. An image helps reveal a disturbance’s shape; a particle sample can retain information about the environment from which the material escaped.
Formation and travel can involve different physics
The new study also finds particle-velocity and magnetic-field variations consistent with an outward-moving Alfvén wave. Such waves are disturbances carried through magnetized plasma. The authors therefore suggest that reconnection can explain the switchback’s origin while waves and turbulence help govern its subsequent propagation.
This offers a way to connect explanations that are sometimes presented as competing alternatives. It also gives researchers a practical method to test: compare the composition of more switchbacks with their magnetic behaviour and likely source environments.
The broader stakes concern how the Sun heats its atmosphere and drives its continuous outflow of charged particles. Those processes underlie the changing space environment around Earth. For now, this is a detailed reconstruction of one encounter, with a promising technique for learning from others.
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