Limited edition photography print by Alaskan artist Shane Lamb. The Aurora Borealis is active all year but can only be seen when the Alaska night sky is dark from August to April. The aurora is a natural light display caused by charged particles from the sun interacting with the earth’s atmosphere. When these particles collide with oxygen, yellow and green are produced; nitrogen produces red, violet, and rarely blue. The colors are also affected by altitude - green/red around 150 miles; purple/violet at 60 miles.