Northern lights: What causes the colors that we see — and don't see?

(NEXSTAR) — Amid a massive solar storm, Americans as far south as Hawaii, Florida, and Texas have had the chance to see the northern lights. For some, it's the first time in nearly two decades that conditions aligned to bring the aurora to their night skies.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, blues, and purples? It's all about wh