What causes the aurora? (Beginner)

Why and how do aurora get created in the night sky of the arctic and antarctic? Why are they usually green in color or occasionally also red or pink or purple. What gives them different colors, and can we see them on other planets?

The aurora are caused by charged particles from the solar wind hitting atoms in the Earth's upper atmosphere. The Sun emits a stream of electrons and protons called the solar wind. These particles interact with the Earth's magnetic field and are funneled towards the magnetic poles, which is why aurora are visible at high latitudes.

The different colors in the aurora come from different atoms being excited. Green aurora come from the excitation of oxygen. Red and blue aurora come from the excitation and ionization of nitrogen atoms.

Aurora has been seen on several planets in our solar system. For example, aurora have been observed on Jupiter, Jupiter's moons Io, and Ganymede, or Saturn.

Just for fun, here is a beautiful video of the aurora viewed from the International Space Station.


This page was last updated on June 27, 2015.

About the Author

Laura Spitler

Laura Spitler was a graduate student working with Prof. Jim Cordes. After graduating in 2013, she went on to a postdoctoral fellowship at the Max Planck Institute in Bonn, Germany. She works on a range of projects involving the time variability of radio sources, including pulsars, binary white dwarfs and ETI. In particular she is interested in building digital instruments and developing signal processing techniques that allow one to more easily identify and classify transient sources.