2012-11-16 19:42:42.000 – Mike Dorfman, Summit Intern
As many facebook fans may have noticed, we had a spectacular aurora display last Tuesday evening (if you aren’t on facebook or haven’t seen these pictures, go here). If you ever wanted to know more about how these auroras form, read on!
We are entering a great time for auroras. In order to have these shimmering light shows in our skies, several things need to happen. Crucially, the sun must be emitting particles from sunspots. These sunspots look like gigantic geysers shooting particles from the sun into space. Our sun goes through cycles in the number of sunspots it contains. We will soon reach a maximum in one of these cycles, so keep your eyes out for more this winter!
Another thing to keep an eye on in predicting auroras is the sun’s rotation. Exceptionally strong sunspots cause unusually strong aurora only if the sunspot is facing earth. Since the sun rotates around approximately every 30 days, if there is an exceptionally strong aurora event, there is likely to be another one in a month once that sunspot is pointing at earth again.
These sunspots shoot charged particles toward earth at several million miles per hour (but still significantly slower than the speed of light). When the particles approach earth, they are deflected along the lines of earth’s magnetic field. As you know, the earth has a north and south magnetic pole, where these theoretical lines in the magnetic field actually enter earth. As the particles ride the lines in the magnetic field either north or south, they will eventually collide with air particles lower in the earth’s atmosphere. Energy is then released in the form of light, which can be different colors depending on how much energy is released.
To keep tabs on whether you’re likely to see aurora tonight, visit the geophysical institute’s website, or just look to the north.
Observer footnote: If you think you have what it takes to predict when wintry weather will hit the area, enter our snow contest. Purchase a ticket for $2 and register your prediction of the day and time that Jackson, New Hampshire will receive its first 6′ of snow in a single storm. If your prediction is correct, you’ll win half of the ticket sale proceeds! The other half will be split equally between the Observatory and Jackson Area Chamber of Commerce.
Mike Dorfman, Summit Intern