I have always wanted to witness the aurora borealis. I even put an app on my phone that is supposed to alert me when the skies are right to see one in NH. I've seen some pictures on the news that people have seen the northern lights over Lake Chocorua a few times this year.
Unfortunately, I have still never observed this amazing phenomenon. But my friend, Keith, did. He recently visited Iceland and sent me a few photos of the northern lights.
So what causes this phenomenon?
Here's the simple answer: The light show we see from the ground is caused by electrically charged particles from space entering the Earth’s upper atmosphere at a very high speed. These particles originate from our star - the Sun. You can learn more abou The Science Behind Them using this link.
And what causes the different colors?
The various colors of the northern lights are related to the types of gas molecules being excited and their altitude. Pale green auroras are the most typical color and are brought on by excited oxygen molecules about 62 miles above the surface of the Earth. Oxygen also contributes to pink and red auroras, but at much higher altitudes, at about 186 miles. The rarest colors, purple and blue, are produced when nitrogen molecules are excited at various altitudes.