At this time of the year, the Central Coast loses a few minutes of daylight each day as we journey into winter. Even though there is less daylight for soccer practice and other outdoor activities, the loss of daylight has an advantage. You just may be able to spot an aurora as nights become longer.
Auroras are light displays in the sky caused by sunspots that unleashed an eruption of highly charged particles, mainly protons and electrons, that traveled away from the sun at extreme speeds. In fact, it only takes about three days for these particles to reach the Earth.
The sky display also is called the northern or southern lights and is seen in far northern and southern hemisphere locations greater than 50 degrees of latitude. In the Northern Hemisphere, the lights are referred to as the aurora borealis, and in the Southern Hemisphere, it’s the aurora australis.
However, during the dark hours on Aug. 12, 2000, when the Perseid meteor shower was at its peak, countless sky gazers throughout California reported seeing the northern lights. Not unexpectedly, many found it difficult to look away from the dazzling aurora borealis in the northern sky to watch for meteors streaking overhead.
This stream of protons and electrons is referred to as the solar winds or plasma. Unlike the winds on the Earth’s surface, the solar wind does not consist of any atoms or molecules. In other words, it’s not the air we breathe.
When fast-moving groups of energetic particles hit the planet’s magnetosphere, they accelerate along the magnetic field lines of the Earth in the upper reaches of the atmosphere, where they collide with gas atoms and give off light. Much like a neon sign that is constructed with different gases in small circular tubes, the many colors of the aurora are caused by different gases in the atmosphere. These gases emit different colors of light when excited by high-energy particles contained in the solar winds from the sun. Molecules of oxygen usually emit green or red light, and molecular nitrogen can give off violet light.
I spent two summers mining for gold back in the mid-1970s in Chicken, Alaska, but never saw the northern lights. That’s because of the perpetual twilight from late May through August. It never really got dark enough to see the lights. It wasn’t until I was on a cross-country flight, on a U.S. Navy P-3 Orion to Alaska in December 2003, that I was finally able to see this amazing sight.
My fellow aircrew and I were walking back to the barracks after having dinner at the Elmendorf Air Force Base dining facility near Anchorage on a bitterly cold night. I remember our navigator saying, “Look at that!” We looked up and saw a moving curtain of blue and green light across the sky. None of us could turn away from this eye-catching sight for the seven minutes that it lasted. According to folklore, the Eskimos thought the lights were from demons’ lanterns searching the heavens for lost souls.
If you’re thinking about traveling north to see the aurora, it occurs most frequently around the spring and fall equinoxes (Sept. 22 and March 22) during the late night or early morning hours.
However, the northern lights are the most intense from December to March, when nights are longer and darker. They are also brighter during a new moon.
The University of Alaska Fairbanks Geophysical Institute has a wonderful website that forecast auroras. Their web link is www.gi.alaska.edu/AuroraForecast.
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John Lindsey’s column is special to The Tribune. He is a media relations representative for PG&E and a longtime local meteorologist. If you have a question, send him an email at firstname.lastname@example.org.