The Aurora Borealis

2016-07-12 19:01:04.000 – Tim Greene, Summit Intern


          Last night, fellow night observer Mike Dorfman and myself were witness to one of the night sky’s greatest shows, the Aurora Borealis. Despite the high auroral activity forecast (a 5 on a 0-9 scale) for North America by the University of Alaska Fairbanks, we were not expecting to see anything too spectacular; certainly nothing like the desktop wallpaper caliber pictures that come out of places like Iceland and northern Canada. Even with a higher auroral activity forecast (say, a 6-8) it is in no way a guaranteed event, thanks to the summit being in the clouds two-thirds of the year. Even so, we stand a better chance of seeing something than does Boston, which was mentioned by name by UAF, because of all the light pollution associated with urban areas. After all, the darker it is, the easier it is to see the light.

Mount Washington Aurora 

What is the Aurora Borealis?

           The Aurora Borealis, often referred to as the Northern Lights, is caused when “solar wind,” which consists of a potentially harmful wave of charged particles expelled by the sun, excites electrons and protons (sub-atomic particles) in a layer of the atmosphere called the magnetosphere. During a magnetic (solar) storm, the sun emits large amounts of solar wind that collides with the Earth’s magnetic field, which acts like a force field, deflecting the radiation and thus shielding the planet. In 1834, a gifted English scientist named Michael Faraday discovered that when a conductor of electricity is in motion relative to a magnetic field, an electric current is induced in the conductor (Faraday’s Law of Induction). The same basic process is used in generators today that convert steam or (indirectly) fuel into electricity and is also responsible for the colorful auroras. This is to say that the waves of solar wind are electrically exciting the magnetosphere, causing it to glow bright green as the charge interacts with oxygen in the atmosphere. As for the reasoning behind the common nomenclature, the aurora tends to stick to the polar regions because of the shape of Earth’s magnetic field. So “northern” lights is somewhat of a misnomer, as there are “southern” lights as well.

          In September of 1859, a particularly strong solar storm was powerful enough that it induced a charge in the conductive telegraph lines between Boston, MA and Portland, ME that allowed two operators to converse without having their batteries powered on for two hours. Nowadays, Faraday’s Law can be detrimental to electronics and the antiquated power grid; on March 13, 1989, a 50-year solar storm plunged Quebec into a blackout that left the entire province in the dark for around 12 hours.

Knowing when to be on the lookout…

          Be sure to check the University of Alaska Fairbanks Auroral Activity Forecast page as well as the NOAA Space Weather Prediction Center’s 30 Minute Aurora Forecast to stay up to date on the auroras. Be mindful of the fact that even three day outlooks are not terribly accurate!


Tim Greene, Summit Intern

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