It is widely believed that auroras are created when particles streaming outward from the sun strike Earth's atmosphere. A key issue with this explanation is that many possible follow-up questions cannot be answered without conceding that the explanation is largely untrue. Without devolving into pedantry, the reality is quite different.
This solar wind is analogous to the wind that powers a windmill, and one of the effects of this windmill - known as our magnetosphere - is to bombard the atmosphere with particles which can produce auroras. Except to a very small extent, these particles do not originate from the sun but are trapped near Earth within our magnetosphere. While viewing images of Earth captured from space, it is easy to convince yourself that our planet sits alone in an empty void. Despite this impression, the environment surrounding Earth is filled with a gas of electrically charged particles and is host to dynamic processes.
Grono, E. M. (2019). Differentiating Diffuse Aurora (Unpublished doctoral thesis). University of Calgary, Calgary, AB. http://dx.doi.org/10.11575/PRISM/37327
