Auroras

Auroras, also known as the northern lights, are a visual display of an intricate dance of particles and magnetism between the Sun and the Earth.  Also known as space weather, auroras are colorful and dynamic.  They can occur when energetic particles from the Sun collide with atoms and molecules in the atmosphere. 

"St. Patrick's Aurora" Image credit: NASA Goddard

Auroras are most generally seen near the Arctic Circle, but they have been visible this year from areas much further south.  The reason for this is that the Sun is at the peak of it's 11 year cycle of magnetic activity!  During solar maximum, the Sun sends out more sunspots, solar flares, and coronal mass ejections (CMEs).  These cause charged particles to burst towards the Earth.  More charged particles interacting with particles in the atmosphere means larger and more intense auroras.

A bright green aurora borealis streams above Earth's surface Image credit: JSC

Auroras can be all kinds of colors!  The color of the aurora depends on the type of gas that is hit by the charged particles from space and where the gas is located in the atmosphere.  Oxygen can produce green between 60 to 120 miles altitude and red above 120 miles.  Nitrogen glows blue from about 60 to 120 miles, but it can also give off both pink and blue light.  Below 60 miles, nitrogen gives the lower edge of the aurora a purple to pinkish glow.  Sometimes the colors even appear to mix.

Aurora in the State of Washington, USA Image credit: Rocky Raybell