Residents of Edmonton, Alberta, had a lot to be thankful for when green auroras graced the sky on October 8, Canada's Thanksgiving Day.
Named after Aurora, the Roman goddess of dawn, the vivid beams of light from aurora borealis result from collisions between charged particles released from the sun's atmosphere and gaseous particles in Earth's atmosphere.
Rays of deep violet edged in lime green are mirrored in the still water of Southland, New Zealand, on October 9.
Earth's magnetic field largely deflects the sun's charged particles, but is weaker at the poles of the Northern and Southern Hemispheres.
Northern and southern auroras typically happen at the same times and are mirror images of one another, moving across polar skies in the same colors and patterns, only reversed. The mirroring of a motion or brightness change happens in less than a fraction of a second.
A soft auroral gleam meanders above the rocks of Norway's Lofoten Islands on October 15. "The ambient light levels from the aurora is all that lights the scene," photographer David Clapp wrote on spaceweather.com.
The vibrant colors strewn across the sky can be compared to streams of electrons inside an old-fashioned cathode ray tube television. Electrons striking phosphorus-coated tubes inside those TVs also create luminous colors and moving patterns.
A violet aurora drapes across the sky near Port Washington, Wisconsin, on September 30.
"Tonight I wasn't expecting auroras," photographer Jennifer Brindley wrote on her blog. But after watching a static green band for an hour, "the show got started, and it was one of the most stunning displays I have ever seen."
Auroras, like gossamer in the sky, glimmer over Iceland's Thingvellir National Park on September 10.
"Aurora season [began] early in Iceland this year," photographer Snorri Gunnarsson wrote on spaceweather.com. Auroral activity occurs in cycles and peaks roughly every 11 years, in tandem with the sun's magnetic-activity cycle. The next peak period is predicted for 2013.