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Below is an explanation of the science of the aurora. If you don’t care then skip to down to the important stuff.
THE SCIENCE STUFF
The sun is the source of the energy which powers all life on earth but is also responsible for a number of other phenomena including the aurora both northern (Aurora Borealis) and southern (Aurora Australasia). The sun is basically a massive hydrogen bomb. This
explosive energy is constantly pushing particles out while the enormous gravity well its mass creates strives to pull everything back in. This tug of war combined with the uneven nature of uncontrolled atomic reactions creates a great deal of turbulence on the suns surface and is largely responsible for things like sun spots (localized decreases in activity) and solar flares (projecting outward explosions on the surface due to a release of magnetic energy) which result in solar winds (energetic particles like electrons and protons which are thrown outward into space think of it as a pot of boiling water). These particles then make the relatively short 93 million mile journey towards earth at about 1,000,000 miles per hour in around 4 days.
Now in large amounts these
particles would not be very good for us or the earth. Fortunately most of these particles are deflected by Earth’s magnetic field and further protection is given by the ozone layer. If not we would probably have died of radiation poisoning long ago which is why it would be wise to consult your solar weather channel
before leaving the planet or get a space ship with some good shielding.
But a small part of those energetic particles are deflected by the magnetic field to the poles. Here they descend and begin crashing into atoms and molecules in the atmosphere.
This means that the atmospheric particles have more energy than normal and are said to be in an excited state. But it is difficult to get them to remain at this state as they naturally regress back to where they were. When this happen the energy has to go somewhere by Newton’s laws, pesky Newton. The energy ends up being given off in the form of a photon of light and so, when this effect occurs millions, billions, trillions of times, the result is a visible light. Different colors caused by different elements and gases at different altitudes. Low altitude oxygen- green, high altitude oxygen- red, nitrogen- blue or purplish red.
So why then do they move rather than just being a glow of color like the sunset. There is still research being done and no solid answer yet but if I had to guess it is because it is a local phenomena which is influenced by a large amount of non static variables. That is to say that if the magnetic field was fixed and unchanging in size and magnitude, the concentrations of energy being emitted from the sun were more consistent, the atmosphere was calm, then maybe it would be a green glow rather than a dance. However the energy is very uneven, the magnetic field shifts and bends (one of the sights below postulates some of that is because of the energy hitting it) and there can be high winds moving everything around at that altitude. So it is my thinking that it is some combination of these that makes it less analogous to the surface between fog sitting on a calm lake and more like a breeze creating ripples on a turbulent river, which is interesting since it has been compared to a river of light.
THE IMPORTANT STUFF
The best time to see the aurora is when the sun is exactly opposite of you. For us that means about 1-3am (‘high’ noon in this part of our timezone being about 1-2pm). I am never up that late on school nights and only occasionally during weekends so I usually only get to see the lights those rare times that it is so good it reaches earlier into the evening or late into the morning.
It is also important to watch the local weather. The biggest best aurora will still be impossible to see through cloud cover. It will also be easier to see during a new moon or when the moon is not up and of course if you can avoid the lights of town or snowgos that would help also.
Though the lights may be active for hours the minute to minute activity fluctuates dramatically. There may be intense activity for 5-30 minutes and then quite quickly fade away lasting a similar duration before resuming again. This means if you see them and are going to tell someone or take pictures you had better go fast because you never know if they will be gone in 10 minutes and may or may not return or if the single display will last hours. The very bright displays are more consistent but may be subject to the same temperamental nature.
We here have noticed that a drop in temperatures is often associated with better lights. Now it could be that this has something to do with atmospheric conditions or that the weather patterns tend to be clearer when it is colder but I believe it has to do more with the scientific laws established by Dr. Murphy ie that the thing you want to see will always be the best at the time you can’t go outside due to work or other commitments or when it is so inhospitable out that you really don’t want to go wait out. The lights also fluctuate seasonally. The image below shows monthly activity. Notice that there is low activity both near the summer and winter solstices. We would not be able to see the lights in the summer regardless owing to it being light all the time (see my other post Hours of Dark) but most people assume that winter is the best. Late September and early October as well as March are the most active times although we tend to do a little better a little closer to winter as there is a better light to dark ratio.
Also interesting there is a predictable pattern to how good a particular year will be. Just like many other natural event, the activity fluctuates in a cycle. The activity peaks every 11 years or so. The last peak was in 2013 and we have been slowly decreasing in activity so by this math 2018-2020 is not the time to go look.
This Thursday is supposed to be pretty good. And since it is supposed to warm up a little I may take my snowgo out in Friday evening and try to take some pictures, weather permitting.
Forecast websites for the northern hemisphere;
http://www.gi.alaska.edu/AuroraForecast/Alaska/20160128 (predictions daily)
http://www.aurora-service.org/aurora-forecast/ (predicts in 15 minute intervals for the current hour and then in 3 hour intervals for the next 3 days)
http://auroranotify.com/ (among other good things has a link to aurora cams in North Pole Alaska which is about 300 miles South East of us)
More on the science of the aurora;
http://asahi-classroom.gi.alaska.edu/color.htm (why different colors)
http://www.wired.com/2008/07/scientists-disc/ (suggests a reason for the dancing appearance of the lights)
http://earthsky.org/space/are-solar-storms-dangerous-to-us (earth’s magnetic shielding)
And of course wikipedia has some good info too.