Between the end of September and the beginning of March they can be seen in the vicinity of the poles (they can also appear in other areas of the world for short periods of time) extraordinary natural phenomena: the northern lights; which are called boreal in the northern hemisphere and austral In the south. In past times it was believed that they were a bridge between the world of the gods and the earthly world, or that they were formed by the spirits of deceased ancestors, unborn children, dragons or flying serpents.
But what are the northern lights actually? In a very basic way, it could be said that they are the effect of the collision of high electrically charged particles from the sun (the “solar wind”) that penetrate the Earth’s atmosphere, generating this luminescent phenomenon. They are ultimately billions of excited atoms that emit tiny flashes of light in the night sky, creating something like a gigantic palette of colors, from green to pink or purple. Those who have seen them live assure that they are a magical and exciting vision. A huge show.
A study published in the journal ‘Nature Communications’ last June presented evidence that the brightest auroras are produced by powerful electromagnetic waves during geomagnetic storms.
The research sought to clear up a question: How are electrons accelerated before colliding with the ionosphere and producing the light of the aurora? The report details that the phenomena known as ‘Alfven waves’ (fast disturbances that emanate from the Sun along the magnetic fields transporting electrodynamic energy) are the cause of the acceleration of the electrons towards the Earth (they can exceed 70 million kilometers per hour), causing the particles to produce that unique light show.
Particles from the Sun
This demonstrated what scientists had predicted for several decades: that energized particles emanating from the Sun (solar explosions and flares) rush along the Earth’s magnetic field lines into the upper atmosphere, where they collide with oxygen and nitrogen molecules, in which they cause an excited state. When these molecules relax they emit light, producing the colorful hues of the aurora.All this happens at about 100 kilometers of altitude.
These spectacular night lights (there are areas where they can also be seen during the day) were named in 1619 by Galileo Galilei, which took its name from the Greek goddess of the dawn, Aurora, and that of the North wind, Boreas. For millennia, auroras dominated by the color red were interpreted as a bad omen.. It was even said that they predicted the death of Julius Caesar (44 BC) and the American Civil War (1860).
The first person to provide a scientific explanation for the polar lights was the Norwegian Kristian Birkeland, but his contribution was not recognized until 1960, long after his death. Every dawn is different. The most common resemble an arc or a green band that stretches across the sky, undulating or twisting.. Its appearance and intensity vary depending on the activity of the Sun and its location depends on the Earth’s magnetic field.
That the auroras appear is something that cannot be predicted with total certainty. It is, after all, a natural phenomenon, like the weather. But it is known where there are more possibilities to see them and where they are best seen.
Where to see ‘the green lady’?
Ideal places to contemplate this fascinating phenomenon in the Northern Hemisphere: Alaska, the northernmost provinces of Canada, Iceland, the Lofoten Islands of Norway, the North Cape, Kiruna in Sweden, Finnish Lapland, northern Siberia in Russia, the Scottish island of Shetland, the Norwegian island of Svalbard and Greenland (where they begin to be seen in August). In some areas the locals call the aurora ‘the green lady‘, as this is usually the predominant color.
Due to the great interest and the increasing number of tourists, in some of these places they have built rooms with glass ceilings and igloos in the middle of nowhere, and safaris are organized with specialized guides to search and “hunt & rdquor; Aurora borealis. Norway, Sweden and Iceland are the destinations most in demand by “hunters & rdquor; of Spanish northern lights.
Some frequently asked questions:
Why do auroras move?
The aurora appears when beams of high-energy electrons pass through the upper layers of the atmosphere. As these beams move forward, the aurora moves as well.
What are the best months to see the Northern Lights?
Statistically, spring (March and April) and fall (September and October) see the highest Northern Lights activity. However, it is also possible to observe them in November, December, January and February.
What is the best time to see them?
Normally the auroras can be seen between 6:00 p.m. and 1:00 a.m., although their frequency is usually higher between 10:00 p.m. and 11:00 p.m.
Why are you more likely to see the aurora on a cold night?
The phenomenon of the northern lights occurs at an altitude above the clouds. On cold nights, the sky is usually clearer, making it easier to see the auroras.
Scientific study on the polar lights (in English): https://www.nature.com/articles/s41467-021-23377-5