Most people know the Northern Lights as one of the prime attractions of the Arctic Circle. For generations, both residents of the Arctic and visitors to the region have been able to witness the night sky come alive in a panoply of blues, reds, and greens. The Northern Lights have colored the imaginations of peoples across the globe for millennia, and with the advent of modern technology, people from all over the world can hop on a plane or cruise ship and see auroras for themselves.
Many people have wondered about the relationship the Northern Lights have with the Arctic Circle, one of the most remote regions of the planet. Read on to learn more about auroras and the Arctic, including why the Northern Lights can generally only be seen in the Arctic Circle.
The Northern Lights and the Arctic Circle
The Arctic Circle is defined as the northernmost circle of latitude on planet Earth and is one of the two polar circles, the other being the Antarctic Circle in the southern hemisphere. The Arctic Circle is defined by a latitude line that is drawn around the North Pole, marking the region in which the center of the midnight sun is visible during the summer solstice on June 21. Large portions of Eurasia and North America fall within the this circle, including lands controlled by the U.S., Canada, Denmark, Iceland, Norway, Sweden, Finland, and Russia.
Auroras are most often visible in this region due to the way the Earth’s magnetosphere works. The sun is best known for providing light and warmth, making life on Earth possible, but the sun also gives off streams of particles known as solar wind, which are highly radioactive and deadly to humans. The magnetosphere, a protective barrier generated by Earth’s magnetic fields, deflects or neutralizes solar wind before it can reach the Earth’s surface, keeping the planet safe.
Much of the magnetosphere extends into outer space, far away from the Earth, but because the magnetosphere is generated by the magnetic fields, it extends into the atmosphere at the North and South Poles, where the magnetic field is generated. When solar wind makes contact with the atmosphere, the resulting chemical reaction is visible as the Northern Lights.
The Northern Lights work by causing air particles to become excited. All matter is composed of atoms, and atoms themselves are composed of protons, electrons, and neutrons. Protons and neutrons are located in the nucleus, the center of the atom, while electrons orbit the nucleus in the same way the Earth orbits the sun. Protons carry a positive electrical charge, electrons a negative charge, and neutrons have no charge.
When charged particles within solar wind impact air atoms, the atoms become excited, meaning that their electrons will move to higher-energy orbits that are further from the nucleus. When this excitement process ends, the electrons will return to their original orbits, giving off a photon—a unit of light—in the process. When this process occurs across many atoms, it generates a large amount of light in the form of an aurora. It’s similar to the way that neon signs work, using electricity to excite atoms of neon gas, causing them to produce light.
The reason why auroras are generally only visible in the polar regions is because these are the only parts of the Earth where the magnetosphere intersects with the atmosphere. The remainder of the magnetosphere extends some distance out into space, meaning that any solar wind that appears there is dissipated before it can enter the atmosphere. Additionally, solar wind particles can only travel along magnetic field lines, invisible lines that connect the North and South Poles; these lines extend outward into space, far away from the atmosphere in parts of the world outside of the Arctic and Antarctic Circles.
The only time auroras can be seen outside of the polar regions is during solar storms. These events are rare and generally cause damage to electrical infrastructure. For example, the Carrington Event of 1859, the last recorded solar storm, caused auroras across much of the northern hemisphere and damaged telegraph lines, causing them to spark or explode.
Another key reason why auroras can generally only be seen in the polar regions is due to day length. The Earth’s axis is tilted, which combined with its revolution around the sun creates the four different seasons: spring, summer, fall, and winter. Summer is the period when one hemisphere is facing the sun more often and receiving more daylight as a result; winter occurs when one hemisphere is facing away, receiving less sun. The closer you are to the North or South Poles, the more extreme the differences in seasons become, with regions in the Arctic receiving near-constant daylight in summer and almost none during the winter. Since auroras cannot form when the sun is shining, the excess darkness during Arctic winters makes viewing auroras far easier.
In addition to the Arctic, auroras also occur in Antarctica, where they are called aurora australis or the Southern Lights. Human sightings of auroras in the southern hemisphere are less common, however, due to a lack of human habitation. Much of the Antarctic Circle is contained with Antarctica itself, which is extremely remote, has a harsh climate, and is difficult to reach due to sea ice and extreme temperatures. Conversely, the Arctic Circle intersects two of the most populous continents in the world, has been inhabited by humans for generations, and is generally easier to reach by land, sea, or air. It also has a warmer climate because the Arctic is composed of sea ice instead of land, in the case of Antarctica.
The Northern Lights have played a large role in human folklore and mythology for generations, as many peoples have observed them in the Arctic. For example, the Inuit of Greenland and Canada historically believed that auroras were caused by deceased humans playing kickball with the skull of a dead walrus. The Vikings believed that auroras were the reflections from the armor and shields of the Valkyries, female warriors who escorted warriors who died in battle to Valhalla, one of the realms of the Norse afterlife.
Due to a confluence of factors, the Northern Lights can generally only be seen in the Arctic Circle. Their beauty and majesty has captivated humans for thousands of years, and with the aid of modern technology, more people from around the world can now travel to the Arctic and see auroras for themselves. If you’re curious about auroras, book a tour and prepare for one of the most magical experiences of your life.