As the spring equinox approaches, northern lights hunters will scour the skies for breathtaking displays of color.

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 ...

The northern lights surprise stargazers by appearing in many forms—from patches or scattered clouds, to streamers, arcs, rippling or dancing curtains. The lights move and change shape and color.