What causes the aurora?

The “northern lights” are caused by collisions between fast-moving particles (electrons) from space and the oxygen and nitrogen gas in our atmosphere.These electrons originate in the magnetosphere, the region of space controlled by Earth’s magnetic field.As they rain into the atmosphere, the electrons impart energy to oxygen and nitrogen molecules, making them excited. When the molecules return to their normal state, they release photons, small bursts of energy in the form of light.

When billions of these collisions occur and enough photons are released, the oxygen and nitrogen in the atmosphere emit enough light for the eye to detect them.  This ghostly glow can light up the night sky in a dance of colors.  But since the aurora is much dimmer than sunlight, it cannot be seen from the ground in the daytime.