Earth Science - Other

An Introduction to the Northern Lights

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"An Introduction to the Northern Lights"
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It's winter in the Great White North; the winter nights are long and cold but they're not completely dark. The Cree say that the spirits are dancing through the sky in great swirls of greens and reds. It's the Northern Lights, and it's the greatest natural light show on earth.

Nowadays, it's known that the brilliant colours of the aurora borealis, also known as the Northern Lights, are caused when the solar wind meets the Earth's magnetic field and ionizes atoms 80 kilometres up in Earth's atmosphere. These atoms and molecules are constantly moving, which causes the Northern Lights to ripple and dance across the sky.

Some colours are caused by the atom losing an electron and being ionized. Others are caused when the atom regains that electron and drops back down to its ground state. Oxygen gives off greens or orange-reds, while nitrogen mostly gives off reds. That's why auroral sheets often look green at the bottom and red towards the top.

Green is the most common colour of the Northern Lights, followed by a pinkish mixture of light green and red. Pure red only happens very high in the atmosphere. Sometimes the reds and greens mix to create a yellow color. Auroras can also be blue, caused by nitrogen returning to its ground state, but that usually happens towards the bottom range of the aurora, so it's very difficult to see.

The Northern Lights usually look like rippling curtains. They can also look like spirals or the kinds of ribbons used in rhythmic gymnastics. They can be seen the farthest south near midnight, when the Earth's facing away from the solar wind. During a strong solar flare, they can be bright enough to read by.

Oddly enough, you can't really see the Northern Lights well near the Geographic North Pole. It's too far away from the Magnetic North Pole, and the alignment with the solar wind and Earth's magnetic field is all wrong.

The beauty of the Northern Lights has long been a secret of the arctic regions. Many people think that there's nowhere else to see them, but that's not completely true. Normally you can only see the Northern Lights if you are inside the circumpolar auroral oval. However, during a major solar storm, you can see the Northern Lights as far south as Hawaii. That's extremely rare, which is probably a good thing. Solar storms which are that strong disrupt satellites and do all kinds of nasty things to communications signals.

The very best place to see the Northern Lights is in the Canadian Northwest Territories, which contain the Magnetic North Pole, at least for now. Unfortunately, you have to brave bitterly cold temperatures in the dead of night to do it.

Thanks to AuroraMAX, that's no longer true. You can now view the Northern Lights online from the comfort of your own home. A large network of live high quality webcams will watch the skies on your behalf. The site will even let you know by email when the viewing of the Northern Lights is especially good. It's a joint collaboration by the Canadian Space Agency, the City of Yellowknife, and Astronomy North, timed to match the solar maximum in 2013 in order to capture some of the highest quality pictures of the Northern Lights ever.

More about this author: Cameron Scott

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