Northern Lights; the Aurora
Borealis
Summer tourists won't have much chance of seeing the famous
Aurora Borealis, the dancing fluorescent ribbons that light up the night sky, enthralling
even "sourdoughs" (old-timers) in Alaska.
The aurora was named after the Roman goddess of dawn, and was long thought to
be produced by sunlight reflected from polar snow and ice, or refracted light much
like rainbows.
The University of Alaska is but one of many facilities where research still
continues into the phenomenon, but so far, research seems to indicate that the aurora is
caused by radiation emitted as light from atoms in the upper atmosphere as they are hit by
fast-moving electrons and protons. The kind of atom determines the color.
It also appears that the sun has an influence: auroras become brighter, more
distinctive, and are spread over a larger area two days after intense solar activity. Two
days is the time it takes the "solar wind" to arrive.
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Best Time to Watch
The "Northern Lights", at their most dazzling from December to March
when nights are longest and the sky darkest, can usually be seen even as far south as
Juneau.
Undulating ribbons of light may shimmer in the sky for hours, like
glowing, dancing curtains of green, yellow and orange or dark red, or magnificent veils
with a full spectrum of colors, and with the altitude of its lower edge 60 to 70 miles
above the earth.
Or the aurora may last 10-15 minutes, twisting and turning in
patterns called "rayed bands", then whirling into a giant green corona in which
rays appear to flare in all directions from a central point, and finally
fade away.
The rarest aurora is the red aurora, like the one of February 11,
1958, which is still talked about today.
An Eskimo tale records that the northern lights are spirits playing
ball in the sky with a walrus skull. Another legend, calls them the flaming torches
carried by departed souls guiding travelers to the afterlife.
The scientific explanation is that the aurora is a physics
phenomenon taking place 50 to 200 miles above the Earth. Solar winds flow across the
Earth's upper atmosphere, hitting molecules of gas lighting them up much like a neon sign.
To study the phenomenon, researchers at the University of Alaska
Fairbanks shoot rockets loaded with special instruments into the aurora from a launch pad
at the Poker Flat Research Range, 30 miles
northeast of town.
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Auroral Displays
The aurora occurs along ring shaped regions around the north and south
geomagnetic poles. The intensity of the displays vary from night to night and throughout
each night.
An intense auroral display can cause many problems on the ground, such as
intense electric currents along electric power lines (causing blackouts) and oil pipelines
(enhancing corrosion). The aurora can disturb the ionosphere and disrupt short wave
communication. Auroral discharge electrons have even damaged the electronics and solar
panels of communications and meteorological satellites, rendering them inoperable.
Because of this, a major cooperative research program, the National Space
Weather Program, studies these effects in an attempt to improve the prediction
of intense auroral disturbances.
Best Aurora Viewing
The aurora is most active late at night or early in the morning,
when the sky is clear and the air chilly. The best time to watch is in spring and fall,
especially February, March, September, and October. One of the best times to look for the
Northern Lights will be when it is dark because of a new moon.
Hardy Alaskans like to put on their parkas and lie on their backs in
the snow to watch. The best viewing happens outside of Fairbanks, away from the city
lights.
Winter tourists might want to try the top of Ester Dome which gives
a view of the sky from horizon to horizon. A nice valley view can be seen in the Chatanika
area.
Closer to town, try the Gilmore Trail looking west, or go to south
Peger Road to escape the streetlights. If you are staying in a hotel, you can head down
the street to wherever it seems a little darker. Winter visitors have been known to stand
or lie in the middle of the Ranch Motel's roomy second parking lot to watch the
lights.
There are also excellent web sites with pictures
and information on the aurora.
Here is one!
http://pamelajoy.com/aurora.html
Joul Mission
Miguel Larsen of Clemson University will arrive in Fairbanks in February
to oversee his Joule mission, named for a unit of energy.
As its name indicates, the Joule mission will measure the heat produced
by the buzzing electrons that make up the northern lights. Larsen believes
his experiment will show that the electrons actually heat up the atmosphere,
a potential problem if they create a drag on satellite momentum.
Joule will launch four rockets in about 20 minutes. The first
rocket, a Terrier Orion, will release a spread of trimethyl aluminum, a
harmless chemical tracer, into the aurora. Two minutes later an
instrumentation rocket will lift off, measuring heat levels in the aurora.
Another tracer and instrumentation pair will take off eight minutes later.
Tracers react with oxygen, producing carbon dioxide, water vapor and
aluminum in the electron stream. The result will be a spectacular 30-minute
auroral display visible from Arctic Village to Anchorage. Cameras at Arctic
Village, Toolik Lake and in the Yukon Territory will record wind patterns
highlighted by the tracers.
Three Rocket UAF Mission
The third mission, using three rockets, will be supervised by UAF
Assistant Professor Mark Conde. It has been years "since UAF has been a
principle investigator on a project," according to range manager Greg
Walker.
With his Horizontal, E-region Experiment, or HEX, Conde, from NASA's
Wallops Flight Facility in Virginia, is leading UAF in its first Poker Flat
attempt since 1995.
