Magnetic ‘flipback’ detected near Earth for first time

In recent years, NASA’s Parker Solar Probe has allowed us to observe the sun up close. Among the probe’s revelations was the presence of numerous bends, or “yaws,” in the magnetic field lines in the Sun’s outer atmosphere. These switchbacks are thought to form when lines in the solar magnetic field that point in opposite directions break and then fit together, or “reconnect,” in a new arrangement, leaving telltale zigzag folds in the reconfigured lines.

In their article published in the Journal of Geophysical Research: Space PhysicsEO McDougall and MR Argall now report observations of a shoelace-like structure in Earth’s magnetic field, suggesting that shoelaces can also form near planets.

Researchers discovered this phenomenon by analyzing data from NASA’s Magnetospheric Multiscale mission, which uses four satellites orbiting Earth to study Earth’s magnetic field. They detected a torsional disturbance in the outer part of Earth’s magnetosphere, the bubble of space surrounding our planet where a cocktail of charged particles called plasma is pushed and pulled along Earth’s magnetic field lines.

Further analysis of the disturbance revealed that it was plasma originating from both the Earth’s magnetic field and the sun. The sun constantly emits plasma, called solar wind, at supersonic speeds in all directions. Most of the solar wind heading toward Earth deflects around our magnetosphere, but a small amount penetrates and mixes with plasma already present in the magnetosphere.

The researchers observed that the mixed plasma structure briefly rotated and then returned to its original orientation, leaving a zigzag shape that closely resembled the switchbacks seen near the sun. They concluded that this flashback most likely formed when magnetic field lines carried by the solar wind underwent magnetic reconnection with part of the Earth’s magnetic field.

The results suggest that switchbacks can occur not only near the sun, but also where the solar wind collides with a planetary magnetic field. This could have key implications for space weather, as mixing solar wind plasma with plasma already present in Earth’s magnetosphere can trigger potentially dangerous geomagnetic storms and auroras.

The study also raises the possibility of better understanding the loops by studying them close to home, without sending probes into the solar corona.

This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.