When you think of the Northern Lights, you probably think of those “aurora-hunters” braving the cold in Alaska in hopes of viewing such a dazzling light display; after all, they are called the Northern Lights for a reason, right?
Strangely enough, however, under the perfect conditions, sky-gazers at all latitudes occasionally have the chance to catch the elusive phenomenon. Coming soon … the Northern Lights are venturing south!
Those lucky enough to have had the chance to personally witness the awe-inspiring beauty of a Northern Lights display would probably describe it as “other-worldly,” and in a sense, it is exactly that.
In reality, the impetus of the Northern Lights is from another world.
The energy that sparks displays of the Northern Lights (aurora borealis) and Southern Lights (aurora australis) is harbored by massive “spots” on the surface of the sun, 93 million miles distant.
While the temperature at the surface of the sun exceeds a stifling 11,000 degrees Farenheight, sunspots tend to be relatively cooler, clocking in at a balmy 7,500 degrees. Much like throbbing bruises that you may sustain from a summertime recreational activity, these sunspots “throb” as well, pulsating with enormous twangs of energy.
These throbs of energy come in the form of solar flares—massive bursts of plasma and superheated gas that explode outwards into space. Frequently accompanying these flares are Coronal Mass Ejections, or CMEs, which, in addition to expelling superheated gas into space, also are characterized by substantial fluctuations in the magnetism throughout an affected region.
At this point, two separate aspects of the flare may affect earth if the flare was indeed earth-directed.
About nine to ten minutes after the Coronal Mass Ejection occurs, high-energy radio emissions reach Earth. Upon contact with our planet, this energy gathers near the poles initially until it is dispersed and diluted. This type of energy has been known to disrupt high-frequency radio waves, particularly those used for aircraft navigation and pilot communication, for which reason the potential for solar flares to occur is constantly monitored by the Space Weather Prediction Center in Boulder, Colorado. In the event that one does occur, pilots are immediately notified and warned that they may experience a loss in radio contact abilities.
Equally important in the equation is the magnetic radiation emitted by the sun in the solar flare, which approaches Earth with a comparatively “slower” one million mile per hour velocity.
Ordinarily, substantial harm would result once this cloud of radiation and magnetism reached earth; in fact, life would cease to exist altogether were it not for a unique layer of protection commonly referred to as Earth’s “natural sunscreen:” the magnetosphere.
Four thousand miles beneath your feet spins a massive orb of liquified nickel, copper, and iron; this molten vat of lava-like metal over time has begun to spin due to the rotation of earth. As such, it has generated a magnetic field hundreds of miles above the planet’s surface that serves to protect Earth from this radiation and magnetism.
When magnetically-disturbed radiation reaches the earth, it gathers around the poles, where the energy is harmlessly converted to and released as light. It is this light that has for centuries sparked mythology and folklore to explain its existence, and one of the most picturesque elements of natural beauty that Mother Nature has to offer.
Only during the most intense geomagnetic storms— rated a G3, G4, or even a G5, on a 1-5 scale— is the earth bombarded with so much energy that it simply cannot “fit” around the poles, and in essence “spills” outwards towards the equator.
Since the aurora borealis depends on sunspots for energy, the likelihood of a particularly strong geomagnetic storm befalling Earth is greatest every eleven years at the peak of the “sunspot cycle” (when sunspots are most numerous). During these times, sunspots crackling and rippling with energy have been known to produce some of the most powerful geomagnetic storms in recorded history.
On October 28, 2005, a historic solar flare collided with Earth resulting in the Northern Lights visiting locations as far south as Texas, New Mexico, and even Florida. Green, purple, and red aurorae shimmered across the night sky practically continuously between sunset and sunrise on the 29th, in many cases with such brilliance that one could read a newspaper without difficulty in the wee hours of the morning by its light.
This year, we are cresting a peak in the current solar cycle; for updates as to when the Northern Lights may shine in your neighborhood, follow Matthew Cappucci on Twitter @MatthewCappucci.
Update on Northern Lights Sightings!
June 22, 2015: The Northern Lights activity has been phenomenal! Here are some photos that I took Monday evening from Massachuetts. Enjoy!