Aurora Displays Continue Despite Passing Peak
When the lights go out in Georgia, Georgians call the electric company. When the northern lights go on in Georgia, Georgians call Alaska scientists.
The day following a display of aurora borealis that hovered above the Lower 48, the information office staff at UAF’s Geophysical Institute received 42 e-mail messages, including this one from a woman who lives in Clinton, Tennessee, near Knoxville:
“About 10:45 p.m. I went outside to feed my dogs, when I looked up in the sky and saw a creepy red glow with finger-like shapes.”
Martha Payne was one of many non-Alaskans who saw an aurora display on the night of November 5, 2001. People saw the aurora that night in California, Wyoming, Pennsylvania, Missouri, New York, Michigan, Nevada, Illinois, New Jersey, Maryland, Wisconsin, and scads of other places.
The November 5 aurora was the result of a major solar flare, an explosion on the sun that caused a shock front in the solar wind. The solar wind is a high-speed stream of charged particles from the sun that collide with molecules and atoms in Earth’s atmosphere to produce the aurora.
“The sun just happened to eject a dense and fast-moving cloud of material in our direction,” said Mark Conde, an assistant professor of physics at the Geophysical Institute and one of several institute scientists who compiles the aurora forecasts at http://www.gi.alaska.edu/cgi-bin/predict.cgi. By monitoring several satellites, including two that are stationed at a point in space between the gravitational pulls of Earth and the sun, Conde is able to predict where the aurora is likely to occur, and at what intensity.
In other aurora-related correspondence, Karen Lundquist of the Fairbanks Convention and Visitor’s Bureau recently relayed a message of concern from a Japanese marketing director. He said some Japanese tourists thought aurora viewing in Alaska might not be worth a trip this winter because the peak of the 11-year solar cycle occurred in the year 2000.
Charles Deehr, a professor emeritus and aurora forecaster at the Geophysical Institute, said that although the peak in the number of sunspots is past, great auroras should continue to blaze above Alaska until at least the spring of 2004. The solar cycle, also called the sunspot cycle, is something like the boom-and-bust populations of snowshoe hares. In a pattern that repeats itself every 11 years for mysterious reasons, the number of sunspots—active regions on the sun—fluctuates in a bell curve. The current solar cycle began in 1996, when only a few sunspots developed. The number of sunspots peaked in 2000, when the monthly average per day was 170. Scientists expect another minimum number of sunspots in 2007, which will be the end of the current solar cycle. Even at what scientists refer to as “solar minimum,” there are many nights of brilliant aurora displays above Alaska each winter. The aurora occurs just as often during solar minimum, but farther north than some of the auroras during the high point of the solar cycle.
Auroras don’t correspond exactly to the solar cycle, Deehr said. Major aurora activity peaks twice during a solar cycle, once when the cycle is nearing its peak and again when the cycle is on the downswing. The second peak of the current solar cycle should occur between now and 2004, Deehr said.
For those viewing the planets with telescopes, Deehr has another tip. The shock wave that caused the great aurora of early November didn’t stop when it reached Earth. According to Deehr’s and others’ calculations, the solar blast should have produced exceptional auroras on Jupiter around November 16th, and on Saturn around November 21st.
