The Northern Lights, or aurora borealis, happen when charged particles from the Sun travel toward Earth and interact with its atmosphere, producing light high above the planet’s surface. Here’s the core idea broken down:

• Solar wind and eruptions: The Sun emits streams of charged particles (electrons and protons) and sometimes large bursts called coronal mass ejections. These particles race through space and can reach Earth over one to several days, depending on the event. [supporting info across scientific explanations]
• Earth’s magnetic field as a guide: When these solar particles approach Earth, the planet’s magnetic field directs many of them toward the polar regions, creating the familiar oval-shaped lights around the magnetic poles. [northern and southern auroral ovals]
• Atmospheric collisions and light: As the charged particles plunge into the upper atmosphere, they collide with atoms and molecules (primarily oxygen and nitrogen). These collisions transfer energy to the atmospheric particles, exciting them. When the excited particles return to their ground state, they emit photons — light that we see as colorful curtains or waves. The specific colors come from different atmospheric gases and the altitude of the interaction (e.g., green from oxygen around 100–300 km, red from higher-altitude oxygen, and purples/pinks from nitrogen). [common descriptions of excitation and emission processes]
• Altitude and structure: The visible aurora typically sits roughly 80–300 kilometers above Earth, though the phenomenon can extend higher. The shapes and movements—curtains, folds, and dynamic “rays”—are shaped by the Earth’s magnetic field lines and solar wind conditions. [general ranges and behavior]
• Timing and activity: Auroras are more frequent and intense during periods of strong solar activity, such as solar flares or CMEs, and they are more often seen near the poles due to the magnetic field guiding particles there. Clear, dark skies away from city lights increase visibility. [conditions affecting visibility]

If you’d like, I can tailor a concise, kid-friendly or sci-tech explanation, or add a short diagram-like description of the process step by step.