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The aurora borealis, a scientific explanation

The auroras, the polar lights, also known as the "Northern Lights" or "Southern Lights", are the result of complex physical processes that occur in the Earth's magnetosphere. They are formed when charged particles from the sun, mainly protons and electrons, collide with the Earth's magnetosphere

Polar lights over Latvia, May 11, 2024. Photo: Lolita Tomsone
Polar lights over Latvia, May 11, 2024. Photo: Lolita Tomsone

In recent days, viewers in southern Europe and even in lower latitudes such as Puerto Rico and southern Florida could watch the Northern Lights show Normally limited to high latitudes, traffic jams were created on the South Island of New Zealand for people who wanted to view the aurora borealis that had encrypted all the way there. A huge eruption of the mass that adorns the sun on May 10, caused it to emit charged particles and those in contact with the earth's magnetic field turn into a magnetic storm that fills the sky with lights of many colors.

The auroras, the polar lights, also known as the "Northern Lights" or "Southern Lights", are the result of complex physical processes that occur in the Earth's magnetosphere. They are formed when charged particles from the sun, mainly protons and electrons, collide with the Earth's magnetosphere. This magnetosphere acts as a shield protecting the Earth from these particles, but some manage to enter through the magnetic poles where the magnetic field is weaker.

When these particles hit molecules and atoms in the atmosphere, they transfer energy to these atoms, causing them to become excited and then release this energy in the form of light when they return to their steady state. The different colors of the aurora are due to the different types of gases present in the atmosphere and the height at which the process occurs. For example, green auroras are formed from oxygen at an altitude of about 100 km above the earth's surface, while red auroras are formed from oxygen at higher altitudes.

An infographic explaining the aurora borealis phenomenon. Illustration: depositphotos.com
An infographic explaining the aurora borealis phenomenon. Illustration: depositphotos.com

The phenomenon is affected by the activity of the sun, especially the solar mass gulf and coronal holes which create a stronger flow of particles from the sun towards the earth. Periods of high solar activity lead to brighter and more visible lights around the world, including at lower than normal latitudes. With the voyages of the explorers, it was discovered that a similar phenomenon also exists in the south - the southern polar aurora and it was called aurora australis.

The term "Aurora Borealis" for the Northern Lights was coined by Galileo in 1619, who combined the name of the Roman goddess of dawn, Aurora, and the Greek name for the North Wind, Boreas. The phenomenon is linked to dawn in various mythologies due to its luminous colors in the sky.

The aurora borealis usually appears in the "aurora zone", which is a narrow band in the latitudes close to the geomagnetic poles. It is mainly visible at night, and is affected by the solar wind that pushes it to the night side of the Earth, creating the "aurora circle" that changes according to the activity of the sun.

The acceleration process of particles is essential to create the aurora borealis. These particles are accelerated as a result of disturbances in the magnetosphere and are the source of the light observed as aurora.

The aurora borealis, especially the northern lights, has a role in folklore since ancient times. Historical records and folklore from around the world refer to the auroras as signs or as a way in which gods or spirits communicate with man, when in Scandinavian mythology, for example, the auroras were considered a reflection of large streams of fish.

But only in modern times was it possible to understand the consequences of the phenomenon. Among the notable events is the Carrington event of 1859, an extremely intense geomagnetic storm that led to communication blackouts and produced extremely bright aurora borealis, so bright you could call it a pine tree. In the Carrington event, telegraph operators used the electrical current generated by the aurora to transmit messages over long distances when the normal power systems were cut off.

Extraterrestrial auroras

The auroras are not limited to Earth and have also been observed on other planets in the solar system such as Venus Jupiter and Saturn, where they are created by similar processes of the collision of the solar wind with stronger magnetic fields. Recently it was possible to measure the phenomenon also in planets outside the solar system.

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One response

  1. How about a kind word about Christian Birkland? The scientific consensus's disregard for anything that smells like space electricity amazes me.

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