Wyoming Aurora Watch 2011

Wyoming Aurora Watch 2011
by Rod Kennedy

Wyoming is not typically known for being “high latitude” or “northern.”  Certainly there are other locations in the continental US that are further north.  So when a website alerts the world about the chance for auroras, or a display of the Northern Lights, we in Wyoming don’t typically get too excited.  After all, we can’t see the Northern Lights in Wyoming, right?  It turns out that this statement is not completely accurate.  While Wyoming is typically not  the best location in the US to view Auroras, it is possible, depending on what is going on 93 million miles away.  Auroras on Earth depend on the sun.

The sun, a star, is a giant nuclear engine that converts millions of tons of Hydrogen into Helium each day.  This process, called nuclear fusion, releases energy as heat and light.  However, the sun also spews out ionized particles and, occasionally, plasma.  The sun is so hot at its core that atoms have their electrons ripped from their nuclei, which makes them ions.  The constant stream of ionized particles from the sun is known as the solar wind.  Plasma is a super heated gas, high in ions but more dense than the solar wind.  The combination of ionized gas combined with ultra-violet radiation from the sun would be lethal to life on Earth were it not for our magnetic field.

Earth is at the ideal distance from the sun for liquid water to exist, and liquid water is a prerequisite for life.  Earth also has a solid inner core surrounded by a liquid outer core; both are made of iron.  The outer core spins around the inner core, which generates a magnetic field around our planet.  This magnetic field acts like a deflector shield against the harmful particles and radiation from the sun and deep space.  So what do ionized gas from the sun and Earth’s magnetic field have to do with Auroras?  Everything.

The magnetic field of the Earth has poles just like a bar magnet.  The magnetic poles of Earth are located somewhat near the actual poles of our planet (although the exact location of the magnetic poles move around relative to the rotational axis of Earth).  The magnetic poles act like giant funnels, allowing the ionized particles from the sun to interact with our atmosphere.  This excites the gases in our atmosphere and they begin to glow, in much the same way that a fluorescent tube glows when electricity passes through the gases within.  Generally these glowing gases are only seen in the extreme northern and southern latitudes of our planet.  However, occasionally the sun ramps up the amount of particles it sends into space.

Our sun goes from solar minimum when the sun is quiet to solar maximum when sunspots are numerous and solar storms are common.  Occasionally the sun erupts in a Coronal Mass Ejection.  CME’s, associated with large sunspots, blast hot, ionized solar material out into space.  If a CME is directed toward Earth there will certainly be an outburst of shimmering auroras.  How far north or south the auroras will be visible depends on how much material the CME shoots into space.  Large solar events make the possibility of seeing auroras in Wyoming more likely.

The sun is a dynamic nuclear engine.  It makes life on this planet possible.  Yet without our “magnetic shield” the surface of Earth would quickly be sterilized by the particles from the sun.  Our magnetic field not only protects us, but also offers us a chance to see the beauty that comes from the interaction between the sun and our home.  As we get further into 2011 we get closer to solar maximum.  Sunspots and solar activity are already increasing.  So keep an eye out, maybe you will see the Northern Lights from right here in Wyoming.

April 2011 Chart

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