
November 19, 2007
Aurora in the Distance

November 19, 2007
Aurora in the Distance
A little universe, just for you
Free PNG · 1080 × 1350 · No account needed
Image rights and credit requirements apply when sharing or reusing imagery.
APOD published November 19, 2007. Credit: Lance McVay. A publication-date match, not a photo taken on your date. Independent of NASA.
Some auroras can only be seen with a camera. They are called sub-visual and are too faint to be seen with the unaided eye. The reason is that the human eye only accumulates light for a fraction of a second at a time, while a camera shutter can be left open indefinitely. When photographing an already picturesque scene above Juneau, Alaska, USA, a camera caught green sub-visual aurora near the horizon. Auroras are sparked by energetic particles from the Sun impacting the magnetic environment around the Earth. Resultant energetic particles such as electrons and protons rain down near the Earth's poles and impact the air. The impacted air molecules temporarily lose electrons, and when oxygen molecules among them reacquire these electrons, they emit green light. Auroras are known to have many shapes and colors.
Image credit: Lance McVay