Here is the second article about the aurora polar. After explaining the auroras creation in space (article here), we will concentrate on observing these auroras.
Where to watch an aurora?
As explained in the first article, the polar auroras are the reaction between the solar winds and the magnetic field of the Earth. The photons reaction, leading to the light of the auroras, is generally at the two extremes (poles) of the Earth towards 65 ° -75 ° of latitude. So you can easily see it in Iceland, Norway, New Zealand, etc. Beware, in the northern hemisphere,the name is aurora borealis and in the southern hemisphere, the name is aurora australis.
For observation, autumn and winter are the most suitable seasons for observation with long nights to have the time to see them well.
How to see them?
The auroras observation is a domain worthy of the gold seeker! Indeed, it is not so simple to see auroras even in countries close to the Arctic Circle. To do this, you need to have certain conditions.
→ It is necessary not to have light. It will be necessary to find an ideal place away from civilization with a wide view of the sky.
→ Locate the North (or the South if you are in the Southern Hemisphere) to find out where the auroras will be
→ Have clear sky! With clouds it is not practical to see them.
→ Have a camera to capture them. It is difficult to see them with the naked eye, so we will have to photograph. For what kind of photos and settings of the camera, I let you read this article: http://www.dennismammana.com/skyinfo/phototips/skyphoto_aurora.htm
How to detect them?
To detect the aurora the best solution is to go through sites specialized in aurora forecasting: https://www.aurora-maniacs.com/previsions-aurores.html
You also have many applications to warn you of auroras depending on where you stand. I can only recommend you My Aurora Forescast which allows you in real-time to know if there is an aurora.
On these sites you will often see the Kp measurement to signify the presence or not of auroras. But what is it ?
Understand the Kp value
The Kp index is used to express the magnitude of geomagnetic storms, ie the disturbances of the magnetic field around the Earth. Now we have seen that the magnetic field disturbance may have as its origin the solar winds at the origin of the polar auroras. Via an algorithm, the value Kp therefore makes it possible to define the probability of having an aurora. Included in 0 and 9, the value means that the disturbance is very low while 9 means high magnetic activity. If you have a magnitude of 6, you are likely to see an aurora, even if you are at an average altitude. For a Kp = 4, you will see auroras, but more in high altitudes. In summary, the higher the Kp, the greater to see auroras in low latitudes.
Attention to a small detail!
The Kp index is measured from 8 magnetometers arranged at different locations in the world. Only 1 of the 8 devices is located in the southern hemisphere, knowing that the predicted Kp is an average of the data from all the magnetometers. So, not very reliable as a clue when one is in the kiwis.
For information, the value G informs about the magnetic activity severity. Each value of G associates a value Kp, it is interesting to remember it due to its use.