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What are the Northern Lights?

Northern Lights, or Aurora Borealis.
The Earth's magnetic field is responsible for producing the northern lights.
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  • Written By: Jane Harmon
  • Edited By: L. S. Wynn
  • Last Modified Date: 30 July 2014
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The Northern Lights, or Aurora Borealis, are glowing bands, circles and streams of colored lights that sometimes appear in the northern latitudes. The southern hemisphere has similar light shows that are called Aurora Australis or the Southern Lights. Both Northern and Southern Lights are referred to collectively as Aurora Polaris. The lights can span the visible, infrared and ultraviolet spectrum, and vary in intensity, duration and extent. They can last a few minutes or all night; Northern Lights can also occur during the day, but sunlight makes them invisible.

The Northern Lights are caused by activity on the sun. Strong magnetic activity is continually taking place on the surface of the sun, and electrons and ions are constantly being thrown out into space. This 'plasma', called the solar wind, is ejected in all directions. It is only when a strong solar wind blows in our direction that Northern Lights occur.

Because electrons and ions are charged particles, they are influenced by the magnetic field of the earth, which sweeps them up as they approach and funnels them toward both poles. The particles spiral down the 'cone' of the magnetic field until they hit the atmosphere, where they interact with atmospheric gases to cause the lights in the sky.

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The stronger the 'storm' on the surface of the sun, the more particles are ejected into space and potentially into our atmosphere. The more particles, the farther south the particles reach before being consumed in a reaction with atmospheric gases. Auroras are visible in the Arctic and Antarctic nightly whenever there is solar storms, and are routinely seen in northern countries with high latitudes. The farther south you go, the less likely you are to see Northern Lights, with the aerial display being visible at the equator only once every century or two.

The colors of the Northern Lights are indicative of how high in the atmosphere the reaction is taking place. Red lights indicate particles reacting at higher altitudes than green, for example. Since the solar wind is always bathing the earth with particles, there is always some upper atmospheric reactions taking place. It's only when the solar wind is particularly intense that the reaction is bright enough to be seen with the naked eye.

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Discuss this Article

chicada
Post 5

@ Alchemy- If you are lucky enough to live somewhere where you can view the northern lights you can shoot nice photos. Use a fast lens (something that can shoot at an aperture of 2.8 or faster). You should also use a tripod and a shutter release cable because you will need to expose for at least 15 seconds or more. Make sure you focus your lens to infinite depth of field and shoot away. Use an ISO of 400 or less, or you might end up with too much noise for the longer exposures.

You should be able to shoot some great northern lights images because we are heading into the peak of the 11 year sunspot cycle. More solar storms leads to an increase in the amount of electromagnetic radiation ejected from the sun, causing excellent light shows.

Alchemy
Post 4

Does anyone know how to take northern lights photos? I have seen the northern lights and tried to take pictures, but every time I shoot the northern lights, they come out as just black photos, or the colors are very faint. I have seen some of the photos in magazines like National Geographic and I want to take pictures that will look like the magazines. Can anyone give me a pointer or two?

Georgesplane
Post 3

I've seen the northern lights on a few occasions from my parent’s house in Vermont. If you happen to be in the state during a solar storm and the sky is clear, look to the north and you may see the northern lights. On most occasions I remember seeing them during the coldest winter nights. When there are no clouds, the air is crisp, and there is no moisture to obscure visibility. The Aurora Borealis are a beautiful sight and are quite memorable.

anon81535
Post 2

this is a great website. It gives just the right amount of information in a clear, neatly written format. keep doing it the way you do guys! You are helping a lot of people.

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