What causes the northern and southern lights?

The answer

Auroras occur when charged particles from the solar wind are funneled by Earth's magnetic field toward the polar regions, where they collide with atmospheric gases. When these particles strike oxygen atoms at high altitudes (above 200 km), they produce green and red light. Nitrogen molecules produce blue and purple hues at lower altitudes. The resulting curtains, arcs, and spirals of light are among nature's most spectacular displays. During intense solar storms, auroras can extend to much lower latitudes - in extreme events, they have been visible as far south as Mexico.