Using the far-ultraviolet camera on board NASA's Magnetosphere-to-Aurora Global Exploration (IMAGE) spacecraft, scientists at the University of California at Berkeley captured a movie of invisible aspects of the aurora during a violent magnetic storm last July.

Earth's aurora viewed with IMAGE spacecraft. Its Wideband Imaging Camera detects far-ultraviolet emissions from molecular nitrogen that has been excited by energetic electrons.

Click here to watch the movie.

The bipolar aurorae are kicked up regularly when the Sun sends bursts of charged particles our way, exciting gases in Earth's upper atmosphere. During particularly stormy space weather periods, the colorful light show can be seen into the middle latitudes of the United States, Europe and elsewhere. At other times the show is confined to the most northern latitudes. (The same phenomenon occurs around the South Pole.)

The sun goes through a roughly 11-year cycle of activity. The current cycle is peaking this year. The peak runs for several months, so auroral activity during 2000 is, on average, the strongest it has been in a decade.

Researchers are only beginning to understand some aspects of the aurora. The IMAGE spacecraft is providing new views, especially of the part that's hard to see, made up of charged particles called protons.

"A significant gap in our understanding of auroras has come from our inability to image proton auroras, which make up a large part of the aurora, because they are very diffuse and are almost invisible to the naked eye," said Berkeley's Stephen Mende, an atmospheric physicist and the lead investigator for the far-ultraviolet instrument. "They are distinctly visible in the far-ultraviolet and, for the first time, we are tracking them to learn more about the structure of auroras."

Launched in March 2000, the spacecraft follows an egg-shaped orbit that, at its farthest point, allows a whole-Earth view.

Researchers who study aurorae told SPACE.com it would take more research before increased understanding can be teased from the new movie and other IMAGE products. Meanwhile, the spacecraft is expected to become increasingly important.

"The orbit of [the] POLAR [spacecraft] is becoming unfavorable for imaging the aurora, so IMAGE will probably be the dominant source of global auroral images for the next few years," said Patrick Newell, a Johns Hopkins University researcher who studies the physics of the magnetosphere.