Geophysicists have found that the Earth fights deadly solar radiation with a plasma punch.

In Science Magazine, a team of geophysicists found another way that the earth’s magnetosphere protects life on the surface.  When high-energy ions in the solar wind threaten to work their way through cracks in the magnetosphere, earth sends up a “plasma plume” to block them.  The automatic mechanism is described on New Scientist as a “plasma shield” that battles solar storms.  They quote Joel Borofsky (Space Science Institute) who says, “Earth doesn’t just sit there and take whatever the solar wind gives it, it can actually fight back.”

Earth’s magnetic shield can develop “cracks” when the sun’s magnetic field links up with it in a process called “reconnection.”  Between the field lines, high-energy charged particles can flow during solar storms, leading to spectacular auroras, but also disrupting ground-based communications.  But Earth has an arsenal to defend itself.  Plasma created by solar UV is stored in a donut-shaped ring around the globe.  When cracks develop, the plasma cloud can send up “tendrils” of plasma to fight off the charged solar particles.  The tendrils create a buffer zone that weakens reconnection.

This plasma shielding was suspected in theory, but has now been observed.  Lead author Brian Walsh (NASA-Goddard) explained on New Scientist:

“For the first time, we were able to monitor the entire cycle of this plasma stretching from the atmosphere to the boundary between Earth’s magnetic field and the sun’s,” says Walsh. “It gets to that boundary and helps protect us, keeps these solar storms from slamming into us.”