What causes geomagnetic storms, and why are they currently visible in the U.S, while locations like Iceland often experience them more frequently?
In: Planetary Science
As with most beauty in the world, it all starts with the sun. The sun is a huge ball of plasma, it is very hot, and has many magnetic fields. Sometimes these magnetic fields become kinked or knotted up and since plasma likes to follow magnetic fields some of the plasma on the surface of the sun follow the kinks and knots.
Well sometimes these kinks become so tight that they kind of just snap think about a rope with a knot in it, if you pull really hard with a lot of force the rope will actually shoot out, with the magnetic fields a similar thing happens and flings some of that hot plasma away from the sun this is called a coronal mass ejection or a CME.
Now this plasma has both an electric charge and a lot of speed, normally the earth has a magnetic field around it that can deflect the solar winds and most of the smaller CMEs, but when the CME is large enough it can actually bend the magnetic field of the earth enough that the plasma of the CME can interact with the upper layers of the atmosphere.
The way it interacts with the upper atmosphere is it discharges some of that electrical charge it has and causes some of the atoms in the atmosphere to produce light.
The bigger the CME the closer to earth the plasma can get, and the closer it can get the more colors you get to see and the brighter they will appear.
The reason places very north or very south see more lights is because the magnetic field of the earth isn’t in the same orientation as it is say closer to the equator, basically closer to the poles the more perpendicular the magnetic field of the earth is to the earth/solar wind, which makes it so a smaller CME is needed to cause the northern or southern lights, to the point where you could see the northern or southern lights with just the standard solar wind.
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