Istory #1 : my trip to the arctic cirlce and seeing the aurora borealis

During the Christmas holidays, I went to the Arctic Circle. It was an opportunity for me to see aurora borealis. A rather coveted phenomenon, nourishing many dreams and many Nordic legends! On the net, we can read than the goal but the ultimate of some travelers is observant these glow at night!

What is an aurora borealis?
An aurora borealis, aurora borealis in scientific name, is a kind of veil that moves in the sky. It can have various colors: mainly green, but also red, blue-purple, or even gray-white. In reality, all the colors of the chromatic spectrum (of the rainbow) are conceivable. However, when you see a picture of aurora borealis multicolored, do not be fooled: it's a montage!

I explain a little more in the article why the aurora borealis can have different colors.

To be honest, when I saw my first aurora borealis, I was not so sure it was actually one! It was very light We almost said a cloud in the night sky ... We must not really trust the photos and videos we can find to identify them ... They are much less bright and saturated (from bright colors) in reality!

The photo reveals some colors of the aurora borealis invisible to the naked eye (photographic comment aurora borealis?).

In fact, beyond color, aurora borealis are classified according to a number of criteria:

the brilliance
conditions (more or less rapid change of appearance)
qualification (if there is one big aurora borealis or several or fragments)
the structure can be homogeneous, like a veil, or more striated, like aligned features
the form (there are really many different northern lights in reality: bow, crown, curtains, stained, veil, etc.)
For more information on aurora borealis, I recommend this site.

Why is an aurora borealis created?
A story of magnets ...
Earth is a kind of big goal. It has magnetic poles (slightly different from the geographical poles). A magnetic pole is the meeting point of the lines of a magnetic field. You are going to ask me what is a magnetic field ...

I will go back to the definition of Futura Science which is understandable:

The term magnetic field refers to a region of space subjected to the action of a force from a lens.

To highlight the magnetic field of a magnet, there is an easily achievable experience. You need iron filings, a sheet of paper and a magnet. Just put a little bit of paper on the sheet of paper, then hold the sheet in one hand and with the other to apply the magnet from below. The iron filings will move, "drawing" the magnetic field of the magnet, as well as on the image.

The compass works with terrestrial magnetic poles: the needle is magnetically charged and the South pole of this needle is "attracted" by the Earth's magnetic north.

It's all well and good, but we'll be back to our northern lights!

... and solar particles!
There are solar winds flowing between the planets. These winds contain solar particles. When these solar particles arrive on Earth, the Earth's magnetic field repels them, and they are then deflected towards the (magnetic) poles.

But to get to Earth, the poor little ones are forced to cross the atmosphere. It's a shock to them! They collide with the ionosphere, the upper layer of the atmosphere, composed mainly of oxygen and nitrogen.

A little like the meteorites, the solar particles ignite when they enter the atmosphere ... And it is the aurora polar (boreal or southern) that is created!

But why all these colors?
The colors of the auroras are due to the composition of our atmosphere. I had a scientific experiment in second. We had to pour different products on a flame: calcium, potassium, strontium, and other stuff in "ium". Well, not that ... there was also copper ... 😃 In short! The flame changed color by chemical reaction. It's exactly the same principle with our small particles.

To quote the Canadian Space Agency:

The color of a dawn depends on the composition of the gases in the earth's atmosphere, the altitude at which the aurora forms, the density of the atmosphere, and the amount of energy involved.

Thus, for example, the violet comes from the nitrogen and the green of the oxygen, the red meanwhile, can come from different elements.

How long does an aurora borealis last?
It's hard to answer this question ... An aurora borealis can last from seconds to hours! And we can not predict ... If you have a direct line with Mother Nature, the easiest way is to give him a phone call ... this is the only advice I can give you!

But from my experience (maybe not the absolute truth ...), there is not just one aurora borealis. At times, the sky is full, but all have different characteristics. Some are very fast, just pass in the sky, like a shooting star, others take the time to settle and can last ... very long!

At other times, the same evening is the complete void ... Really hard to anticipate ...

Where is it possible to observe this phenomenon?
Aurora borealis occurs in the northern hemisphere. On the other hand, southern lights appear in the southern hemisphere. To designate both phenomena at once, we speak of polar auroras.

• In the Northern Hemisphere? But uh ... it's huge! You do not have more precise?
• Patience!

It is between 60 ° and 75 ° latitude that you are most likely to see this type of night glow. But this corresponds to many places: northern Scandinavia (Norway, Sweden, Finland and Iceland), Greenland, northern Canada, Alaska, northern Russia, and so on.

Scotland can also be a good destination (video evidence below). And we have even already observed aurora borealis in France! Everything depends on the solar activity, the famous "winds".