Take a look back at some of the EPODs our viewers found particularly eye-catching. Today, and every Saturday, EPOD invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers’ Choice polls. Join us as we look back at these intriguing and captivating images.

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Photographer: Richard Kelly; Richard's web page

Summary Author: Richard Kelly, Jim Foster

The photo above showing a brilliant, electric green aurora was captured in Churchill, Manitoba in mid February 2010. Auroras occur when energetic particles streaming out from the Sun are guided along the Earth’s magnetic field lines toward both the north and south magnetic poles. If oxygen molecules get in their way, green light is emitted. Though Churchill is more than 1,700 mi (2,735 km) from the North Pole, it’s only approximately 1,200 mi (1,930 km) from the geomagnetic north pole. Thus, there are more opportunities to view auroras here than from locations in northern Eurasia that are actually closer to the North Pole. The photo was taken during the Canadian CoReH2O Snow and Ice (Can-CSI) science experiment.

Photo details: the photo was taken with a Nikon D90 modified for infra-red photography (although these photos were taken with the visible light-only filter attached). Settings: 30 second exposure; wide aperture; ISO 600; Focal Length: 18.0mm (35mm equivalent: 27mm).