AURORA BOREALIS. This astronomical event usually visible from the poles of our planet could be observed in the sky of France this night from Monday February 27 to Tuesday February 28, 2023. The most beautiful images and the explanation of the phenomenon.
[Mise à jour le 28 février 2023 à 18h04] The meteorological phenomenon of the aurora borealis, mainly observed in the Nordic countries, made its appearance in the nights from Sunday to Tuesday in the northern France, in Pas-de-Calais, in the Brittany and Burgundy regions. The United Kingdom, Scotland, Germany and of course Iceland were also able to enjoy the show! Outside Europe, photographers from Canada or the United States were also able to immortalize the celestial spectacle. Discover our photo slideshow of the most successful aurora borealis this night:
The mechanism of the aurora borealis, discovered at the beginning of the 20th century by meteorologists, is the result of intense solar activity. When the sun emits waves of highly charged particles that come into contact with the magnetosphere (space surrounding the Earth beyond the ionosphere)the interaction causes this magnificent luminous phenomenon.
This phenomenon is particularly visible near the poles (northern regions) because the Earth’s magnetic field deflects these particles towards the “polar horns”. Thus, the North, Alaska, Iceland, the North of Canada and the Scandinavian countries are the places on Earth most affected by these polar auroras, almost every day. The phenomenon appeared exceptionally in France because these particles, this time endowed with greater energy, deviated in the atmosphere at low latitudes, far from the poles.
Where to see the Northern Lights in France?
France is a country located well south of the Arctic Circle. It is for this reason that the probability of observing an aurora borealis there is extremely low. However, this phenomenon occurs from time to time as was the case this night from Monday February 27 to Tuesday February 28, 2023 because the Earth’s magnetic field was shaken by the solar winds!
However, this type of event was limited to regions located in the north of the country such as the departments of Pas-de-Calais, Brittany, Nord and Alsace. These aurora borealis were very difficult to observe with the naked eye and were usually only spotted on camera shots.
What are the conditions for observing the aurora borealis?
To fully enjoy an aurora borealis, it is recommended to move away from sources of light pollution. Look for a place located away from urbanized areas. Watch the weather to favor a night when the sky is clear or the clouds are not too thick. Finally, you can monitor the Kp index which will let you know the probability of an aurora borealis occurring.
It is impossible to accurately predict the date and time of the next aurora borealis in a given location. On the other hand, certain indices make it possible to know the probability that this type of event occurs. For this, we are generally interested in the Kp index, which provides information on the intensity of the magnetic disturbances to which the Earth is subjected. The planetary Kp index, updated every three hours, is available on the website SpaceWeatherLive.
To find out if the aurora borealis is to be expected, it is generally advisable to follow the evolution of this indicator which reflects the occurrence ofsolar flares. The latter emit solar winds which can, if they cross the trajectory of the Earth, be at the origin of spectacular aurora borealis depending on their intensity.
What is an aurora borealis?
The Northern Lights are atmospheric phenomena that can be observed at the Earth’s poles. They manifest as luminous clouds that seem to dance across the night sky. If they have been interpreted in different ways in history and according to folklore, these luminous veils are actually linked to the activity of the Sun which regularly bombards the Earth with energetic particles. When these reach the Earth’s atmosphere, they interact with the gases that make up our atmosphere, causing these celestial manifestations.
What is the cause of the Northern Lights?
The Sun emits electrically charged particles in all directions, including towards our planet. The latter is protected from these particles by the Earth’s magnetic field, a veritable invisible shield generated by the movements of the Earth’s liquid core. When the solar wind encounters this protective barrier, it deforms, but generally prevents particles from entering the atmosphere.
However, sometimes stronger than usual solar winds occur. This is particularly the case during solar flares of great intensity. In this case, the magnetic field is disturbed and the particles emitted by the Sun cross this invisible barrier. It is the meeting of these particles with the gases of the Earth’s atmosphere that generates the aurora borealis and australis.
When energetic particles emitted by the Sun enter the atmosphere, they encounter the particles that make up the gases in the upper atmosphere and collide with them. “Electrons and protons then excite the atoms that make up these gases and, through a phenomenon called ionization, transmit an electric charge to them. It is by returning to their initial state that the atoms of the Earth’s atmosphere will release light energy , in the form of photons” explains the magazine Geo. It is therefore these electrical interactions that generate luminous and colored bands above our heads.
What explains the color of the aurora borealis?
Sometimes green, sometimes red or pink, the aurora borealis and australis are adorned with various colors and can offer very different shows from one day to the next. “When they hit, these particles spurt out light. The colors differ according to the stimulated atoms, from red to green, passing through purple or yellow. The gradients can represent all the shades of the chromatic spectrum” explains the magazine National Geographic. The color of an aurora borealis depends on the altitude at which it forms as well as the nature of the gases present at this height.
Thus, when they form at low altitude, around 100 kilometers, the auroras can appear in the form of a green veil in the presence of oxygen, pink or red in the presence of nitrogen or even blue or purple in the presence helium or hydrogen. At higher altitudes, around 300 to 400 kilometers, oxygen can also give a red tint to the glows.