I saw the northern lights for the first time a few years ago, and the experience was completely different from photographs. Photos flatten them into static curtains. In person, they move — rippling, pulsing, sometimes sweeping in seconds across the entire sky. Understanding what causes them makes watching them even stranger and more beautiful.
I’ve spent a lot of time researching this topic, and here’s what I found.
Ever noticed this pattern in your own life?
The Physics in Plain Language
The Sun continuously streams charged particles — mainly electrons and protons — outward in what’s called the solar wind. Earth’s magnetic field deflects most of this stream, but near the magnetic poles, the field lines converge and funnel particles downward into the upper atmosphere.[1]
Related: earth science fundamentals
I believe this deserves more attention than it gets.
When these energetic particles collide with oxygen and nitrogen atoms at 100–300 km altitude, they excite the atoms — boosting electrons to higher energy states. When those electrons drop back down, they release that energy as light. The color depends on the atom and the altitude:
References
Sources cited inline throughout this article.
