The Aurora Borealis
The light show often begins simply, as a pale yellow-green luminous band that arches across Alaska's night sky. Sometimes the band will quickly fade and disappear. Other nights, however, it may begin to waver, flicker, and pulsate. Or the quiescent band may explode and fill the sky with curtains of celestial light that ripple wildly above the northern landscape. Growing more intense, these dancing lights take on other colors: pink, red, blue, or purple. At times they appear to be heavenly flames, leaping across the sky, or perhaps they're exploding fireworks, or cannon fire.
Where to See Them
The Fairbanks area is one of the best places in the world to see the aurora borealis—commonly called the northern lights. Here they may appear more than 200 nights per year; they're much less common in Anchorage, partly because of urban glare.
As you watch these dazzling lights swirling from horizon to horizon, it is easy to imagine why many Northern cultures, including Alaska's Native peoples, created myths to explain auroral displays. What start out as patches, arcs, or bands can be magically transformed into vaporous, humanlike figures. Some of Alaska's Native groups have traditionally believed the lights to be spirits of their ancestors. According to one belief, the spirits are celebrating with dance and drumming; another says they're playing games. Yet another tradition says the lights are torches, carried by spirits who lead the souls of recently deceased people to life in the afterworld.
Where Do They Come From?
During Alaska's gold-rush era some non-Native stampeders supposed the aurora to be reflections of ore deposits. Even renowned wilderness explorer John Muir allowed the northern lights to spark his imagination. In 1890, Muir once stayed up all night to watch a gigantic, glowing auroral bridge and bands of "restless electric auroral fairies" who danced to music "too fine for mortal ears."
Scientists have a more technical explanation for these heavenly apparitions. The aurora borealis is an atmospheric phenomenon that's tied to explosive events on the sun's surface, known as solar flares. Those flares produce a stream of charged particles, the "solar wind," which shoots off into space. When such a wind intersects with Earth's magnetic field, most of the particles are deflected; some, however, are sent into the upper atmosphere, where they collide with gas molecules such as nitrogen and oxygen. The resulting reactions produce glowing colors. The aurora is most commonly a pale green, but its borders are sometimes tinged with pink, purple, or blue. Especially rare is the all-red aurora, which appears when charged solar particles collide with oxygen molecules from 50 to 200 miles above Earth's surface.
Alaska's long hours of daylight hide the aurora in summer, so the best viewing is from September through March. Scientists at the University of Alaska Geophysical Institute give a daily forecast from late fall to spring of when the lights will be the most intense at auroraforecast.gi.alaska.edu.