NASA has identified two types of auroras—fast-pulsating and flickering. Pulsating auroras flash on and off within seconds. Flickering auroras, however, pulse even faster, up to 15 times a second. Scientists want to investigate why auroras form "holes" or dark patches.

A train ride to witness the northern lights across the Arctic Circle is more than a mere journey; it is a magical, life-altering experience. The spectacle of the auroras, which attract tens of thousands each year, is unparalleled.

A newly compiled dataset of nearly one billion images of auroras is helping researchers categorize—and perhaps ultimately anticipate—the Northern Lights.