Encore - Aurora Borealis from Barrow, Alaska
September 16, 2017
Today and every Saturday Earth Science Picture of the Day 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.
Photographer: Ignatius Rigor
Summary Authors: Ignatius Rigor; Jim Foster
The photo above shows a bright green aurora commanding the night sky over Point Barrow, Alaska as observed on March 9, 2012 with the camera facing northeast. It was taken during the NASA BRomine, Ozone, and Mercury Experiment (BROMEX). Intense solar storms (solar flares) the first week of March ignited these striking northern lights. High-speed particles (solar wind) generated by solar flares are guided along magnetic field lines as they near the Earth. These particles excite electrons primarily in oxygen and nitrogen atoms of the upper atmosphere above the poles. Oxygen emits most strongly in the green portion (530 nanometers) of the electromagnetic spectrum. In this case it’s mostly the oxygen atoms that have been excited. That’s the Moon, not the Sun, rising over sea ice in the Arctic Ocean.
Photo Details: Camera Model: NIKON D7000; Lens: Tokina AT-X 116, PRO DX; Focal Length: 11mm; F Number: f/3.5; Exposure Time: 15 seconds; ISO Speed Ratings: 100; Software: Adobe Lightroom 4 Macintosh software.