If you saw the northern lights — either with your own eyes or with the help of your phone — you may have noticed an array of colors. But what causes the different shades of greens, reds ...

With more sightings of the northern lights across the U.S. than usual in recent years, now is an excellent time to make the trek to a Dark Sky Place. Even if you don't see the rainbow of colors ...

The lights are most visible above the magnetic poles of the northern and southern hemispheres. They appear in a variety of colors ... streams of light, rainbow-like arcs, or active auroras ...

Green and red light are emitted by oxygen. The color of nitrogen is blue and purple. You can find more northern light details on the Space Weather Prediction Center, which provides an aurora ...