NARRATOR: Our Sun is constantly blasting huge amounts of hot plasma out into space. All those charged particles have a big effect on everything in their path. So what’s protecting Earth from the solar wind and solar storms?
Earth’s thick atmosphere provides some defense, scattering and absorbing solar particles before they reach the surface. But, our planet also has a secret weapon-- a strong magnetic field it projects into space, mostly generated by molten iron alloys moving in Earth’s outer core.
The area of space where the magnetic field interacts with the solar wind is called Earth’s magnetosphere. Its shape constantly changes, as it is bombarded by solar particles.
As positively charged protons and negatively charged electrons enter the magnetosphere, most of them are deflected around Earth, long before they reach the atmosphere.
The magnetosphere really gets tested when big solar storms, carrying more plasma and traveling at higher speeds, are on a collision course with Earth. While most of the plasma is deflected, some of it gets trapped in the magnetosphere, and funnels back toward Earth along field lines emanating from the poles.
As charged particles from the Sun collide with nitrogen and oxygen molecules in our atmosphere, they create the cosmic light shows known as auroras.
The bigger the storm, the further from the poles auroras can be seen. Some storms are so big they interfere with satellites, cause planes to alter their routes, and can create other problems. The vast majority of the time, these inconveniences are pretty minor. But the next time the solar version of a “perfect storm” overwhelms Earth’s magnetic shield, we might not be so lucky.