Many people are completely enamored by the Northern Lights, but not many people understand what causes them. 

 

The Northern Lights are not seasonal in the sense that we perceive seasons on Earth; they actually have to do with the Sun and its magnetic cycle. In a nutshell, what happens is this: as the Sun rotates, it drags its magnetic field around with it until the magnetic field gets really tangled up.

 

Loops of magnetic field lines end up getting stuck in the Sun’s outer layer (called the Photosphere) and attract the charged gas (plasma) there. Eventually, enough magnetic energy builds up such that those loops break and send the plasma free to fly through space, sometimes towards us.

 

If that Sun plasma reaches Earth and couples correctly with Earth’s magnetic field, the Sun plasma travels down the Earth’s magnetic field lines to the magnetic poles, essentially “raining” down. As the Sun plasma starts to rain down, it begins to interact with the higher levels of Earth’s atmosphere; in particular, the ionosphere. In the ionosphere, the Sun plasma undergoes nuclear reactions with several types of oxygen ions, releasing light as each electron in each atom changes energy levels from the reactions.

 

That light is what we see as Northern Lights, or Aurora. It usually looks green, but deep and bright purples can creep in there if the interactions are strong enough. Iceland happens to be at one of the best latitudes to see the lights in the Northern hemisphere, so if anything is happening, we can usually see it from here. 

 

Unfortunately, Iceland only has darkness for half of the year so they aren’t visible in the summer. It isn’t because they aren’t happening; it’s because it’s too bright outside to see them if they are. The lights tend to be strongest around the vernal and autumnal equinoxes, or in March and September, because of the alignment of Earth’s magnetic field with respect to the Sun’s magnetic field. However, they can happen any time it’s dark and clear enough to see them.

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All photos were taken with a Canon EOS Rebel XT, with a variety of settings. Join me as I learn how (and how not) to photograph them, and enjoy the wonder of the ´´Norðurljós.´´ 

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