What causes the northern lights to appear?

The northern lights, or aurora borealis, are caused by charged particles from the sun, primarily electrons and protons, streaming toward Earth as solar wind. When these particles reach Earth, they interact with the planet's magnetic field, which funnels them toward the polar regions. As the particles collide with gas molecules in the upper atmosphere, mainly oxygen and nitrogen, they excite those molecules, causing them to release energy as light. Different gases produce different colors: oxygen typically creates green and red hues, while nitrogen produces blue and purple tones. Solar storms and high sunspot activity intensify the aurora by sending larger bursts of charged particles toward Earth, making the lights more vivid and visible at lower latitudes.