Green Aurora Over Lake Superior

What if your horizon was green? If you've got a camera, take a picture!
That was the experience of Jeff Hapeman last week when visiting the
Pictured Rocks National Lakeshore in Michigan. On a quiet night toward
the northern horizon over Lake Superior was a long lasting diffuse green
aurora. The above image was taken in an effort to capture the sense of
wonder one gets when watching an auroral display. Auroras are sparked by
energetic particles from the Sun impacting the magnetic environment
around the Earth. Resultant energetic particles such as electrons and
protons rain down near the Earth's poles and impact the air. The impacted
air molecules temporarily lose electrons, and when oxygen molecules among
them reacquire these electrons, they emit green light. Auroras are known to
have many shapes and colors.