Scientists Detect “Switchback” Phenomenon In Earth’s Magnetosphere For The First Time

The Earth’s magnetosphere is a protective shroud that blocks charged particles and cosmic rays blasted out by the Sun. The four unmanned spacecraft that make up NASA’s Magnetospheric Multiscale Mission (MMS) have spent nearly a decade studying how the magnetosphere interacts with the Sun’s magnetic field. Now, they have discovered an unusual zigzag in our magnetosphere called a magnetic switchback, the first that scientists have discovered near Earth. 

The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

The study was led by Emily McDougall, an astrophysicist who conducted the work while at the University of New Hampshire. McDougall’s research focuses on a phenomenon called magnetic reconnection, in which nearby magnetic fields—like those of the Earth and the Sun—interact and release huge amounts of energy. These energy releases, far from our planet, kickstart processes that produce phenomena here on Earth, such as dramatic auroras. 

Switchbacks are kink-shaped plasma structures that form out of reconnection events. Switchbacks have been previously found near the Sun, by missions like the Parker Solar Probe, but not near Earth.

McDougall found the switchback in the magnetosheath, a layer just beyond the magnetosphere, where solar wind, diverted by the magnetosphere, flows. The switchback contained high-energy electrons that appeared to have come from the Earth’s magnetic field, on the Sun-facing southern end. 

This Earth plasma was mixed with Sun plasma inside the switchback. The four MMS probes were able to measure how the field rotated, the speeds of the particles inside, and assess how these compared with existing turbulence and reconnection models. 

The MMS team intends to send the probes on additional sorties through the area, which will hopefully provide more information on how switchbacks amass and what shifting energy conditions trigger them. Large reconnection events can trigger disruptive geomagnetic storms, which can interfere with terrestrial power grids and radio links. They can also pose risks for crewed spacecraft and satellites in Earth’s orbit. 

Now that McDougall’s work has shown reconnection events happening in our planet’s immediate neighborhood, studying these phenomena will become easier. Previous studies had to rely on probes operating far closer to the Sun. With more accessible, relevant testing data closer to home, scientists will be able to improve their predictions of which reconnection events are big enough to disrupt manmade systems and which will pass by harmlessly. 

The study was published in the Journal of Geophysical Research.