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Kelsey M,

What causes all of the colors seen in auroras?

Hi Kelsey.
Auroras happen when electrons from up in the Earth's magnetic field come down into the Earth's atmosphere. They hit molecules of gas in the atmosphere. The molecules get energy from being hit bu the electrons and then send that energy back out again as light. This is how neon lights work.

 Each different kind of gas (in this case nitrogen and oxygen - the elements that make up most of our atmosphere) gives off a particular set of colors. Oxygen produces the greenish light often seen in auroras and sometimes red light higher up. Nitrogen sometimes produces the red light seen lower down.

Here are some web pages that talk about this some more.
http://www.exploratorium.edu/learning_studio/auroras/difcolors.html
http://webexhibits.org/causesofcolor/4D.html

Cheers,
Terry

Hi Kelsey,

This is a good question!  The most simple answer is that different atoms in Earth's atmosphere will glow in different colored lights.  The aurora is made when particles from space hit Earth's atmosphere (60 miles above Earth's surface) and cause it to glow.  When different types of gas are hit with the particles, they glow in different colors: red, green, blue, yellow... etc. 

The tricky thing is that gases can glow in different colors and what colors they give off when they glow depends on the energy of the particle that hits them as well as how they release that energy.  For example, oxygen gas with just one oxygen atom, will glow in both red and green and these are the colors most often seen in the aurora.  This is how we know there is oxygen gas 60 miles above Earth's surface.  Nitrogen gas with two nitrogen atoms will glow in many colors, such as red and blue. 

Laura

Hi Kelsey,

Good observation. The color of light corresponds to the energy the photons carry.
In the case of auroras the energy emitted is determined by the precipitating particles
as well as  the atmosphere (temperature, composition). How and how much energy
the  particles gain inside the magnetosphere is still one of the  hot topics in space physics.
What  makes it so complicated is that there is a  chain of events that lead to auroral displays.
Since these events cover large distances in a very short time they are  very difficult to observe
simultaneously.  I am currently working on a new NASA mission that will launch 5 small spacecraft
and set up about 20 cameras to just do that: determine the timely order and location of those events
that are important to generate auroras. 

Sabine