DISCUSSION: In Norway last week, close to the 70th parallel (and so far north that the sun won't appear again in the sky until January 15th), photographer and aurora tour guide Marianne Bergli captured perhaps one of the most colorful and picturesque stills of 2017; a dazzling green and pink aurora above a snow-capped island chain.
Most auroras are green; a glow caused by energetic particles released from the Sun striking free oxygen atoms anywhere from 60 to 175 miles (about 100 km to 300 km) above the Earth's surface. The beautiful pinks, however, reveal something else: when energetic particles penetrate farther below into Earth's atmosphere, they can collide with nitrogen molecules below 60 miles (100 km) and give off a pink color.
As the Sun radiates, it emits energetic particles in every direction from the Sun's upper atmosphere, or corona; this stream of particles is commonly known as the solar wind, and the increase in speed of its particles can be directly linked with regions in the Sun's upper atmosphere known as coronal holes (where open magnetic field lines in the Sun's upper atmosphere allow particles to more easily stream out.) It is this faster stream of solar wind particles that interact with Earth's upper atmosphere to create such wonderfully vivid auroras.
The solar wind's increase in speed is shown by three-day NOAA's Deep Space Climate Observatory (DSCOVR) data, which you can find here.
The solar wind velocity began to increase on December 17th and passed the 500 km/s threshold at about 5:00am EST, a threshold that would make for an elevated solar wind.
Other than solar wind activity, the surface of the Sun is blank and shows no sunspots - this is our 99th day without sunspots in 2017 and the most days without sunspots in a year since 2009.
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© 2017 Meteorologist Chris Stubenrauch
Marianne's Heaven on Earth Aurora Chaser Tours. N.p., n.d. Web. http://www.chasethelighttours.co.uk. Accessed 18 December 2017.
SDO / Solar Dynamics Observatory. N.p., n.d. Web. https://sdo.gsfc.nasa.gov. Accessed 18 December 2017.