An aurora (plural: aurorae or auroras; from the Latin word aurora, "sunrise") is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere). The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth's magnetic field into the atmosphere. Most aurorae occur in a band known as the auroral zone,[1][2] which is typically 3° to 6° in latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole defined by the axis of the Earth's magnetic dipole. During a geomagnetic storm, the auroral zone expands to lower latitudes.
Aurorae are classified as diffuse or discrete. The diffuse aurora is a featureless glow in the sky that may not be visible to the naked eye, even on a dark night. It defines the extent of the auroral zone. The discrete aurorae are sharply defined features within the diffuse aurora that vary in brightness from just barely visible to the naked eye, to bright enough to read a newspaper by at night. Discrete aurorae are usually seen only in the night sky, because they are not as bright as the sunlit sky. Aurorae occasionally occur poleward of the auroral zone as diffuse patches[3] or arcs (polar cap arcs[4]), which are generally invisible to the naked eye. (wikipedia)
When to Go
Since you can only see them at night, you want to come when there is the most darkness—from September until about April 20; that’s when there are: 1) frequent displays, 2) clear skies, and 3) generally mild weather.
Where to Go
While you can potentially see them all over the state, the most reliable spot is Fairbanks. Up and inland, Fairbanks is geographically under the "aurora oval," where auroras are seen most frequently. You can even take excursions several hours north from there, offered by operators such as Northern Alaska Tour Company.
How-To Tips
The aurora is unpredictable, and no one's entirely sure when—or where—it's going to appear. But here are some tips to give you the best odds of seeing the aurora in Alaska.
Look at the Right Time of Day
Start looking about an hour and a half after sunset, but peak auroral activity is between 10 p.m. and 2 a.m. solar time. (Solar time is 2.5 hours after clock time during daylight saving time (and 1.5 hours after during standard daylight time. That means the best time for seeing the aurora during Alaska's winter is 11:30 p.m.–3:30 a.m. with the peak at 1:30 a.m. During Alaska's spring and fall (September and March), the best time to view the aurora is 12:30 a.m.– 4:30 a.m.
Look for the Right Weather Conditions
If it's clear and dark enough to see stars, there's a chance you'll be able to see the aurora. If there's even partly cloudy skies? You have a chance, but it needs to be a strong aurora for you to see it. Check out these two prediction tools:
- Look at the weather forecast for the town you're in.
- Get the aurora forecast from the UAF Geophysical Institute. (http://www.alaska.org/things-to-do/northern-lights-viewing)
The northern lights are just about the only thing that could get Alaskans to stand outside without a coat in January.
But there the lights are, flipping and waving through the sky in shades of green, purple and red. And there are Alaskans, calling neighbors outside for a look and putting cameras on tripods in the middle of the night.
Usually the aurora borealis appears to the north of the viewer, but occasionally it seems to be directly overhead even as far south as Anchorage, which sits just north of 61 degrees north latitude.
Many Anchorage aurora fans drive north during the winter in search of brighter and more colorful lights, sometimes ending up in Talkeetna at the foothills of the Alaska Range. (Leon Unruh)
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