Auroras - Living with a Star
Premieres Tuesday February 11, 2003

Still closer to Earth are molecules of nitrogen which shimmer with purplish light. All the colors we see are chemistry in action. And the dynamic and fast-moving shapes - the rays, the arches, the arcs stretching for thousands of kilometers - are caused in ways we still don't fully understand by the physics at work as Earth's magnetosphere responds to the energy and influence of the solar wind.

Images courtesy of Jan Curtis

Pink auroras on Jupiter and Saturn:
courtesy STScI/Hubble Space Telescope & NASA

We know we've understood the key forces which shape Earth's aurora because they help us understand why other worlds which lack planet-wide magnetic fields, like the Moon or Mars, also lack auroras. Giant planets, like Jupiter, Saturn and Uranus, which have strong magnetic fields, also have auroras. And the pink-colored aurora we see at Jupiter are also those we might expect from the prevalence of the gases hydrogen and helium in Jupiter's atmosphere.

Syun-Ichi Akasofu of the International Arctic Research Center, UA Fairbanks, and a discoverer of the auroral sub-storm during the 1957 International Geophysical Year, even thinks that looking for the tell-tale green of oxygen in the aurora of distant planets might be a way to discover signs of life on distant worlds!

Syun-Ichi Akasofu compares the aurora to neon lights.

Damage to power grids could affect
large areas of North America:
courtesy the IMAGE mission, NASA, and University of Michigan

But auroras are more than scientific curiosities and light shows in Earth's skies. In 1989 a rare, blood-red aurora appeared much farther South than usual. Up North in Canada, a major utility, Hydro Quebec, lost power to 6 million customers. The two phenomena were, in fact, directly related. An unusually strong aurora had induced DC (direct current) currents in the AC (alternating current) power grid. Generators, as far south as New Jersey, fried.

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