Jimmy Westlake: Seeing the majestic Northern Lights
November 29, 2011
Solar activity is on the rise, which means so are the chances of seeing the Northern Lights from Colorado. Alert sky-watchers might have gotten a taste of things to come last month when faint auroras were seen from much of the northern U.S. The aurora borealis, or Northern Lights, is seen regularly from the far northern latitudes of Canada and Alaska but is rare from mid-northern latitudes like Colorado.
Auroras are created when protons and electrons from the sun get tangled up with Earth's magnetic field. The process begins deep inside the Earth's core, where molten iron churning around generates powerful electric currents. These electric currents generate a magnetic field that surrounds Earth with a protective bubble called the magnetosphere. Charged particles from the sun typically are deflected around Earth by this magnetic field.
The sun, too, generates a powerful magnetic field, but because the sun's equator rotates faster than its poles, it gets all twisted and tangled. Every 11 or so years, the sun's twisted magnetic field lines snap and reconnect, releasing enormous amounts of energy in the form of solar flares and coronal mass ejections, or CMEs.
A large CME can blast billions of tons of charged particles into space, and if Earth gets in the way, our magnetic field can become overloaded with these charged particles as it guides them toward Earth's magnetic poles. When they collide with Earth's upper atmosphere over the poles, the solar particles cause the air molecules to emit light in much the same way that the gas in a fluorescent light tube glows. Red, green, blue and yellow rays and curtains of light can flicker and wave across the sky.
The sun now is awakening from a longer-than-usual solar minimum. Sunspots, flares and CMEs are becoming more common as the sun approaches its next maximum in activity sometime near 2014.
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Will you be ready to catch the next colorful display of the Northern Lights when they appear over Colorado? NASA sponsors a solar activity and aurora forecast website called http://www.spaceweather.com where you can get information on impending auroral storms and other celestial events. You can even sign up for an aurora alert automated phone call from http://www.spaceweather.com that will wake you in the night if an aurora is visible.
The Colorado Mountain College SKY Club will host a special free Public Astronomy Night program entitled "The Majestic Northern Lights" at 7 p.m. Dec. 7 in the CMC Library. If the weather permits, telescope observation of Jupiter and the moon will follow the indoor program. For more information, call 970-870-4537.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Check out "Jimmy's 2012 Cosmic Calendar" of sky events at http://www.jwestlake.com. It features 12 of his best astrophotographs and a day-by day listing of cool celestial events that you and your family can have fun watching in 2012. Proceeds from the sale of Cosmic Calendars support the CMC SKY Club.