Why Do the Auroras Occur?
The Northern and Southern Lights hold a lot of mystery. How do they dance in the sky like that?
The aurora borealis (Northern Lights) and the aurora australis (Southern Lights) are breathtaking sights to see. People travel from all over the world just to experience this miraculous event for themselves, but many don’t understand why exactly it occurs.
The auroras can be found at high latitudes, near the north and south magnetic poles. They occur when solar winds interact with different elements in the planet’s atmosphere.
These winds come from the sun at speeds of around 1 million miles per hour and reach our planet about 40 hours after leaving the sun.
When these solar winds reach the planet, they follow the lines of magnetic force from the core of the earth. They quickly flow through a layer of the atmosphere known as the magnetosphere, which contains highly-charged electric and magnetic fields.
As the solar winds enter the atmosphere, they interact with atoms of oxygen and nitrogen anywhere from 20 to 200 miles above the planet’s surface. The colors of the aurora depend on which atoms are struck and the altitude of the interaction.
- Green: oxygen, below ~150 miles in altitude
- Red: oxygen, above ~150 miles in altitude
- Blue: nitrogen, below ~60 miles in altitude
- Purple: nitrogen, above ~60 miles in altitude
The auroras appear to “dance” because they move with the atmospheric currents and the shifting magnetic and electric fields in the atmosphere.
