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Northern Lights

Everything you need to know about Aurora Borealis

General Information

Flickering curtains of green, red, yellow or blue color dancing on the night sky. Most people that ever had the luck to experience Northern Lights will agree that this show performed by mother nature is simply breathtaking. Northern Lights are definitely one of the most spectacular light show on earth that is created by nature. They are indeed an elusive, magical phenomenon. When you for the first time see them dancing around the entire sky above you and change shapes and colors within a short time period, you will understand what we talk about.

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Although they can possibly occur at any time of the day, Northern Lights are usually seen at night when darkness occurs. It has been said that the lights can be so bright that one is able to read a newspaper underneath them during the night. The best time of the year to see them is between late fall and early spring. However, since nature is not always predictable it is not possible to make forecasts on aurora activity far in advance.

 

Northern Lights or Aurora Borealis?

The scientific name for Northern Lights is Aurora Borealis. The name Aurora Borealis is Latin and can be translated into “the dawn of the north”. Aurora was a Roman goddess of dawn and Boreas is Greek for the north wind. During the 13th century, Norwegians used the name “Northern Lights” for the first time. In the following both names – Aurora Borealis and Northern Lights – are both used.

Northern Lights in Iceland

How were the Northern Lights explained in ancient times?

Since Northern Lights are such a magical phenomenon it is not a surprise that there exists a tremendous amount of stories and legends about them. People through different time periods have explained the lights, among other things, as a sign from dead women, light from gods’ kingdoms, something evil and dancing spirits. Early documentation of Northern Lights can already be found during the Stone Age. Carvings displaying Northern Lights have been found in a cave, located in today’s France. However, the question about what causes them was long left unanswered.

Attempts to explain the Northern Lights continued to change over time and it wasn’t until the end of the 19th century that someone succeeded. Kristian Birkelund, who was a Norwegian scientist finally found the correct explanation for this phenomenon. His theories were based on many expeditions in Norway and on the photographs he took of Northern Lights during these expeditions. He was actually the first one to capture Northern Lights on photographs. A short sum up of his explanation can be found in the Section “How are they formed” below. Aurora is not only visible on earth, but also on a handful of other planets such as Jupiter. Moreover, there is a lively discussion whether Northern Lights have their own sounds or not. However, until this day this discussion has not been settled yet.

 

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How are they formed?

In short, aurora is created by the collision of electrons originating from the sun with different gases in the atmosphere of the earth. This collision causes light to be released which we then see as aurora.

In a bit more detail, auroras are caused by solar activity and the way it interacts with the magnetic field that surrounds our planet. In addition to this, the gases oxygen and nitrogen that can be found in the atmosphere of the earth play a role. Solar particles (electrons and protons) originating from the sun travel continuously to the earth and hit the magnetic field of the earth. Due to magnetic forces, these solar particles are guided along the protective shell of the earth. As a result of this process, the particles reach two ring-shaped regions which are referred to as the Auroral Ovals. One of them is located close to the North Pole and the other one close to the South Pole (see picture below). For different solar activity, the size of those regions vary. The greater the activity the greater is the area. The current Aurora Ovals can be found here.

 

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During cycles of increased solar wind activity, which are referred to as Solar Flares and which are caused by a higher amount of sunspots, enlarged numbers of particles travel between the sun and the earth. When they hit our magnetic shield they somewhat change the form of it. The Magnetopause, which normally prevents the solar particles from entering the earth’s atmosphere, “breaks”. As a result of this, a number of charged particles enter the atmosphere of the earth at the Auroral Ovals and interact with gases – namely oxygen and nitrogen. During the process of calming down after being excited by the sun particles, light is produced by the molecules of the gases. If a large enough number of collisions occurs, this light is visible as aurora for us. The whole process is showed in the graphic below.

Aurora is, in fact, a proof that particles do affect the magnetic field of our planet.

Note: this is a simplified explanation of the whole process. For a more scientific explanation, we recommended this video.

The different Colors of Northern Lights

The color the Northern Lights display can vary, although green is by far the most common color. The color they display depends on the type of gas that is involved in the process as well as the energy level the sun particles embody. While green, yellow and red colored aurora is associated with excited oxygen, blue and purplish colors are caused by interaction with nitrogen.

 

Whether a Northern Light is green or red depends on the altitudes at which the oxygen emits. For different altitudes, the energy level the particles have can vary. The higher the altitude is the higher is the energy level. If the collision occurs at a relatively high altitude, the color of the Northern Light is red. For this to happen, a higher intensity of the activity of the solar wind is needed. On the other hand, green Northern Lights are created at lower altitudes and hence at lower energetic levels. Therefore, a lower degree of solar activity is needed to be present in order to create green northern lights.

The blue and the purple colored Northern Lights are rarely seen. That is because Northern Lights need to go above the shadow of the earth and be directly exposed to the light of the sun to appear in these colors. In order for this to happen, the sun needs to be located in a certain position. The sun needs to be positioned slightly below the horizon in a so-called deep twilight. A coloring of this style is referred to as “resonance scattering” and can also happen when the light of the sun is reflected by the moon.

Yellow Northern Lights are caused by a combination of the different colors mentioned above.

 

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The different shapes of Northern Lights

The aurora can appear in many forms. The basic forms are: Arcs, Corona, Diffuse, and Drapery. Drapery is the shape that is seen most often. Drapery aurora is commonly described as flickering curtains. Arcs have shapes that remind us of rainbows, while Corona is seen in the shape of a crown. Diffuse aurora is only seen on rare occasion and does not take on a shape with specific features. Moreover, they cannot be seen easily, without the help of certain devices.

Scientists have not yet found an exact answer to the question of what causes these different shapes. It is, for example, believed that the shapes depend on the electrons’ source and the way these electrons incident into our atmosphere. This process varies due to the fact that the magnetic field of the earth is responding in an ever-changing way to the particles originating from the sun. Moreover, the relative position between the Northern Lights and the person observing plays a role in determining the shape of the Northern Light that can be seen.

 

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How to take photographs of the Northern Lights

Cameras that can manage to take pictures of the aurora have to have a manual setting. The camera needs to be useable in high ISO setting. Older cameras, 5 years and older, are not as good in high ISO setting like the newer ones, so you should have a good photosensitive lens

The lenses that are best to use are panoramic/wide and with a large diaphragm. You can use a tight/close-fitted/close lens but if you want to have some landscape in the picture panoramic/wide lenses are best. The lens needs to have a focus indicator as well to see where the focus is because autofocus does not work in this situation. This indicator is on most finer lenses and is situated on top of it.

How to adjust everything

The camera should be adjusted to manual mode. The diaphragm should be adjusted to the largest diaphragm the lens provides. In fact the lower the diaphragm number is the better, 1.4, 2.0 or 2.8 are the best ones.

The shutter speed should be adjusted to 4 seconds in the beginning, sometimes you need a shorter time but most of the time you need longer time, about 4-15 seconds. It is not recommended to go over 20 seconds because it will develop something called star trail in the stars.

ISO (photosensitive/sensitive), should be adjusted to ISO 800 in the beginning. Most of the time ISO 800-3200 is used but the lower the number the better the quality and better colors. You can experiment with this number, it all depends on how strong the aurora is.

The lens is adjusted to manual focus and if it has image stabilizer on the lens you must turn that off and also if you have some sort of a filter fastened on the front of the lens, like UV-filter or something like that you should take that off as well. The focus should then be adjusted to infinity, there the window with the focus indicator should appear. If the focus is not stable in the lens you should turn the focus circle to the left or right, depends on the manufacturer which way the infinity setting is, and then a little bit back again, but only a little bit. It might be hard to get focus in these situations but if you have trouble with it, you can zoom out the lens to the max and try to focus on a star and then zoom back when the focus is there. The camera is put on a tripod and if you have something called shutter release then it is good to use that but not necessary.

White balance is best to adjust on AW (auto white balance). The aurora is moving fast and the color changes also quickly so this setting is the best in this situation.

So, the basics are:
  • Put the camera on the tripod, take filters off of any and turn off the no shake
  • ISO should be adjusted to 800-3200.
  • The diaphragm should be as big as the lens provides.
  • Shutter speed should be 4-15 seconds.
  • White Balance adjusted to auto white balance.
  • Take extra batteries with you, because it will empty fast in the cold.
  • Flashlight if possible so you can see what you are doing while adjusting the settings on the camera.

 

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