Star Wheel

National Geographic Best Space Pictures of 2012 Editors Pick

Photograph by Alex Cherney, TWAN

A long-exposure picture—posted to the night-sky photography community The World at Night (TWAN) in November—captures the stars' nightly swirl while auroras set the horizon aglow over Australia's Mornington Peninsula.

Auroras are born when the sun sends charged particles, known as solar wind, speeding toward Earth's atmosphere, where they slam into oxygen and nitrogen atoms in the ionosphere above the planet's magnetic North and South Poles. The energy released by these collisions creates glowing colors some 60 to 620 miles (97 to 1,000 kilometers) aloft.

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