The aurora borealis, or northern lights, is one of nature's most spectacular displays. These shimmering curtains of light occur when charged particles from the sun interact with gases in Earth's atmosphere.
The sun constantly releases a stream of charged particles called the solar wind. When these particles reach Earth, they're channeled toward the poles by our planet's magnetic field. As they collide with atmospheric gases, energy is released as light.
Different gases produce different colors. Oxygen at high altitudes creates red auroras, while at lower altitudes it produces the familiar green. Nitrogen contributes blue and purple hues.