(The Aurora Borealis, or Northern Lights, shines above Bear Lake, Eielson Air Force Base, Alaska.)
Aurora is a luminous glow of the upper atmosphere which is caused by energetic particles that enter the atmosphere from above. Auroras, also called the northern lights are natural light displays in the sky, usually observed at night, particularly in the polar regions. They typically occur in the ionosphere and are also referred to as polar auroras. In northern latitudes, the effect is known as the aurora borealis, named after the Roman goddess of dawn, Aurora, and the Greek name for north wind, Boreas.
(Aurora australis in Antarctica. Photo © Samuel Blanc.)
The aurora borealis is also called the northern polar lights, as it is only visible in the sky from the Northern Hemisphere, the chance of visibility increasing with proximity to the North Magnetic Pole, which is currently in the arctic islands of northern Canada. Aurorae seen near the magnetic pole may be high overhead, but from further away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the sun was rising from an unusual direction.
(Red and green Aurora in Fairbanks, Alaska. Photographed by Mila Zinkova.)
The aurora borealis most often occurs from September to October and from March to April. The northern lights have had a number of names throughout history. The Cree people call this phenomenon the "Dance of the Spirits." Aurorae can be spotted throughout the world. It is most visible closer to the poles due to the longer periods of darkness and the magnetic field.
I thought this was such a cool photo of the Aurora, as seen from space. (Aurora australis captured by NASA's IMAGE satellite and overlaid onto NASA's satellite-based Blue Marble image.)
I have never actually seen the Aurora, but it is something on my bucket list of things to see in my lifetime. I have always wanted to visit Alaska, and I hope to make a trip during the peak time for Aurora sightings.
2017 Total Eclipse of the Sun
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