1 of 11
Electric HoodoosA curtain of green auroras ripples over hoodoo rock formations near Drumheller, Canada, early Monday, Labor Day in the U.S. The same night, similar shows enlivened skies over many high-latitude countries across the Northern Hemisphere.Last Friday a solar flare exploded off the sun, launching a giant cloud of charged gas—a coronal mass ejection, or CME—toward Earth. About 48 hours after NASA's Solar Dynamics Observatory had detected the eruption, the CME, travelling faster than a million miles an hour, slammed into Earth's magnetic field, sparking the auroras.When a CME, or solar wind, enters the upper atmosphere, its charged particles smash into and break up gas molecules, which give off energy in the form of the so-called northern lights (or in the Southern Hemisphere, southern lights).The colors a sky-watcher sees depend on the type of gas being hit and how high it is. For example, the green aurora pictured was the result of oxygen-atom collisions about 60 to 120 miles (100 to 200 kilometers) up.(More pictures: "Multicolored Auroras Sparked by Double Sun Blast.")—Andrew Fazekas
Photograph by Darryl Reid

New Aurora Pictures: Solar Flare Sparks "Snakes," "Spears"

Sparked by a Friday solar flare, Sunday night's green-and-purple sky show seemed to glimmer with snakes, spears, and a fiery phoenix.

Published September 8, 2012