As solar wind approaches the Earth, it meets the Earth's magnetic field. ... In the ionosphere, the ions of the solar wind collide with atoms of oxygen and nitrogen from the Earth's atmosphere. The energy released during these collisions causes a colorful glowing halo around the poles—an aurora.

What causes auroras to happen?

The short answer to how the aurora happens is that energetic electrically charged particles (mostly electrons) accelerate along the magnetic field lines into the upper atmosphere, where they collide with gas atoms, causing the atoms to give off light.

Where auroras are formed?

An aurora is a natural light display in the sky, particularly in the high-latitude (arctic and antarctic) regions, that is caused by the collision of energetic charged particles with atoms in the high-altitude atmosphere.