Aurora Borealis at the park, Denali National Park and Preserve, 2012.

Galileo named the aurora display in 1619 after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas. All aurora (on Earth) are the result of electrons colliding with the upper reaches of Earth's atmosphere. Specifically, these electrons have escaped the sun at sunspot regions, which are spots on the sun's surface where the sun's magnetic field has inhibited convection. This results in a reduced surface temperature at that spot/region. These sunspot regions then aggressively throw plasma, or solar wind, into space. After about 40 hours, these winds reach Earth and result in auroras. Interestingly, variations in aurora colors are due to the type of gas particles involved in these collisions. Yellow-green, the most common color, results from oxygen molecules at low altitudes under 60 miles. The rare all-red auroras are also oxygen but occur at very high altitudes up to 200 miles. Nitrogen gas produces blue or purple-red aurora. Solar storms and sunspots that cause the most brilliant auroras vary with the solar cycle and occur about every 11 years. Aurora Borealis is the Northern Lights, while Aurora Australis is the Southern Lights.

northern lights aurora landscape aurora borealis polar aurorae denali national park and preserve denali national park park result sunspot regions wind aurora colors aurora display aurora australis earth electrons spots altitudes miles national parks gallery high resolution alaska

2012

National Parks Gallery

https://npgallery.nps.gov/

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