an image representing the ionosphere, one of the layers of earth's atmosphere. this is where auroras happen

The active, changing layer

An interesting layer called the ionosphere overlaps the mesosphere, thermosphere, and exosphere. It’s a very active part of the atmosphere, and it grows and shrinks depending on the energy it absorbs from the sun. Its name comes from the fact that gases in these layers are excited by solar radiation to form “ions,” which have an electrical charge.

Parts of the ionosphere overlap with Earth’s magnetosphere. That’s the area around Earth where charged particles feel Earth’s magnetic field.

In the ionosphere, charged particles are affected by the magnetic fields of both Earth and the sun. This is where auroras happen. Those are the bright, beautiful bands of light that you sometimes see near Earth’s poles. They’re caused by high-energy particles from the sun interacting with the atoms in this layer of our atmosphere.

Visit other layers in Earth's atmosphere.

Where would you like to go?

a landscape with trees and mountains
article last updated December 8, 2015
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