The Northern Lights (Aurora Borealis) arise from interactions between the Sun and Earth’s atmosphere. Solar activity sends charged particles toward Earth, which are guided by the planet’s magnetic field toward the polar regions. When these particles collide with atoms and molecules in the upper atmosphere, they transfer energy and cause those gases to glow, producing the colorful curtains and arcs you see in the night sky. The effect is most vivid near the magnetic poles and can vary in color depending on the type of gas and the altitude of the interaction.

Key points

• Source: The Sun emits a continuous solar wind—charged particles (primarily electrons and protons) that travel through space. Disturbances such as coronal mass ejections or solar flares can intensify the stream hitting Earth, amplifying auroral displays.

• Mechanism: As solar wind particles reach Earth, they are funneled by the geomagnetic field toward the polar regions. There they collide with atmospheric gases (mainly oxygen and nitrogen), exciting them and causing photon emission—this is the aurora.

• Appearance: The lights appear as undulating curtains or arcs, whose colors range from green and pink to red and violet, depending on the gas species and altitude. The lowest emissions commonly occur around ~80 km above the surface, with higher-altitude interactions producing red or purple hues.

• Geography and timing: Auroras are most frequently observed around the Arctic and Antarctic circles, in regions collectively known as auroral ovals. Activity heightens during stronger solar wind conditions, but can be seen at lower latitudes during powerful geomagnetic storms.

If you’d like, I can tailor this to a specific location or season, or explain how to maximize your chances of seeing them.