Alaska is one of the best places in the world to see the northern lights, or aurora borealis, dancing overhead. Caused by supercharged solar particles colliding with the earth's atmosphere, these ethereal streamers of green, white, purple, blue and even red light draw awestruck travelers from all over the world. The best time to see them is from late August through April. Make sure you ask your hotel staff to wake you up if the aurora comes out, or take a tour that specializes in spiriting you away from light pollution for the best possible views of the aurora.