Northern lights, or aurora borealis, are glowing shafts of light you see in the night sky.These light displays can be seen in both the northern and southern hemispheres, and are called polar lights. Southern lights, or aurora australis, is the term given to the same phenomenon in the southern hemisphere.The northern lights are a fantastical sight: shades of green and red dancing across a starry sky! Although they look otherworldly and surreal, the auroras are a very natural phenomenon. The polar auroras occur near the south and north pole because the Earth’s magnetic field is the strongest at these points.As pretty as they look, the science behind the polar lights or aurora polaris suggests that the phenomenon actually causes disruptions in our power grids and satellite operations. In simple words, the northern lights are caused by reactions between particles in the atmosphere, which interrupt signals that are necessary for several key human operations.Many people keep track of the climate and travel to viewing spots just to catch a glimpse of the northern lights. The northern lights occur very frequently in places near the north pole, such as Greenland and Canada. If you live in the northern U.S., it is very much possible for you to witness this colorful display with your own eyes!Significance Of The Northern LightsThe northern lights have a significant impact on the Earth’s magnetic field and all technologies that rely on it. Read on to understand how this phenomenon happens and its aftereffects.The sun contains billions of gas particles, such as hydrogen and helium. Due to the extreme heat in its outer layer, known as the corona, some of these particles become ionized or charged and escape into the atmosphere.These electrically charged particles or electrons and protons escape the surface of the sun. These particles that travel through space are known as the solar wind.A solar wind that travels at a very high speed and has a high density of particles is called a solar storm.When the sun ejects a large cloud of gas, a large amount of charged particles travel towards the Earth at lightning speeds. This is called a coronal mass ejection.When such a solar storm enters the Earth’s atmosphere, the ionized particles react with the gases present in Earth’s magnetic field.The magnetosphere, or the Earth’s magnetic field, is a protective layer in the upper atmosphere. It acts as a shield from harsh solar winds.The magnetic field is essential for the survival of life on Earth because solar wind or solar flares can have damaging consequences.As a result of constantly streaming solar wind, the magnetic field is shaped like a comet with a tail stretching behind it.Most of the cosmic radiation that hits the Earth’s atmosphere is redirected back into space. The charged particles that manage to hang back react with the gases in the atmosphere resulting in the aurora borealis and aurora australis.The northern lights happen when these charged particles or plasma react with mainly oxygen atoms and nitrogen molecules in the atmosphere, producing colored lights in the night sky.In a way, the northern lights act as a visual guide of the invisible magnetic field that surrounds and protects the Earth.However, when the aurora borealis occurs, it messes with our satellites and electrical power grids.Without the planet’s magnetic field in place, the international space station wouldn’t be able to function, nor would air transit be possible during auroral storms!Legends And Myths About The Northern LightsPeople didn’t always know what the auroras were, which paved the way for many legends and a lot of speculation regarding the magical light show in cultures around the world.Aurora is the name of the Roman goddess of dawn. According to the ancient Greeks and Romans, the northern lights were the goddess riding her chariot across the sky to alert her siblings, gods of the Sun and the Moon to the breaking of dawn.Chinese culture has perhaps the oldest and richest history of events surrounding the aurora. According to Chinese legend, a woman by the name of Fubao was sitting by a bay when the sky turned brilliant silver and made everything around seem alive. Fubao was so moved by the sight that she gave birth to Emperor Xuanyuan, who is known as the ancestor of all Chinese people.Aboriginal Australians used to believe that the aurora australis was associated with the spirit world and often referred to it using terms that connoted fire.The Vikings from the Nordic countries in northern Europe and the North Atlantic used to both celebrate as well as fear the lights, believing them to be earthly manifestations of Norse gods.According to the Inuit community of northern Greenland, the northern lights were celestial games played by the spirits of the dead.The auroras have also been interpreted as omens of death. For example, people in Hudson Bay, Canada used to believe the lights were actually lanterns of demons hunting for souls to kill.Inuit communities in Alaska, where the lights are a common occurrence, used to carry knives to protect themselves from the malevolent spirits of the aurora borealis.Facts About The Northern LightsThe northern lights and southern lights actually occur at the magnetic poles of Earth. This is because the charged particles move around along the magnetic lines when the stream of plasma hits Earth’s upper atmosphere.The colors produced by the aurora borealis are affected by altitude. At altitudes of 150 mi (241.4 km) and above, red light occurs. At lower altitudes below 60 mi (96.6 km), blue or violet color is produced. The green color is brightest between 60 - 50 mi (96.6 - 80.5 km).Green light means that the cosmic particles are reacting with atmospheric oxygen at a certain altitude.Pink light suggests the reaction of oxygen at higher altitudes, however, this is a less common occurrence.Blue or red light is produced when reactions involving nitrogen happen in the earth’s upper atmosphere.It takes around two to three days for the solar winds that cause the northern lights to reach the planet’s magnetic field.Although the aurora borealis can occur any time of the day, it is only visible in a clear and dark sky.High northern latitudes are the best locations to view the aurora borealis during winter. Places like Alaska, Canada, and Scandinavia are optimal viewing locations.Residents of Fairbanks, Alaska frequently witness spectacular displays of the aurora borealis.The northern lights appear in many shapes and forms, such as the homogenous arc, rayed arc, rising vapor column, and corona.A homogenous arc refers to an aurora that is characterized by non-specific glowing streaks that lay in the sky. This occurs when the auroral zone is least active.When the northern lights are a bit more active, the aurora is formed as striations across the sky. They look like the fine pleats of a curtain, or vertical rays.The rising vapor column aurora is an optical illusion - it looks like a column of smoke that seems to have made contact with some point on Earth, like a mountaintop. This happens because an aurora of this form takes place 60-187 mi (96.6-300.9 km) above the Earth!The corona is a form of aurora where you will see rays of light splaying out in all directions from a single point. The only way you would spot this type of aurora is if you were directly beneath an active aurora curtain. Again, this is an illusion caused due to the human perspective. In reality, the aurora rays would be a lot farther away and not have actually converged.Northern lights occur on other planets too. Using ultraviolet light imagery, the Hubble Space Telescope has captured images of northern and southern lights on Jupiter and Saturn, which are even more vivid than the ones we see on Earth!Noise Made By The Northern LightsStargazers and scientists alike have wondered for centuries if the fantastical northern lights are capable of producing sounds audible to the human ear. Read on to learn what science has to say on the matter!Many people have claimed to have heard certain noises at exactly the same time an aurora occurred.In the 1930s, there were testimonies by residents of the subarctic Shetland Islands that compared the sound of the northern lights to ‘rustling silk’.Similarly, people from northern Canada and Norway have also claimed to hear the northern lights.The scientific community has largely disregarded the theory that the northern lights could have sound over the decades.It was during the second International Polar Year 1932-33 that scientists discovered that auroras occur hundreds of miles above the surface of the Earth. This reinforced the belief that any noise associated with the northern lights was only an auditory illusion.It was in a Finnish study conducted in 2016 that scientists finally seemed to collect evidence of auroral noise. A researcher recorded noises that were supposedly made by the northern lights 230 ft (70.1 m) above ground level!One of the popular theories about noise suggests that it is caused by something called a ’temperature inversion layer’.Simply put, temperature inversion layers are warm air layers that contain charged particles from the ground and the high atmosphere.The theory suggests that when the solar flares that cause the northern lights hit these layers of air, the charged particles lose their charge. This causes the release of a sound akin to radio static, explaining the ‘claps’ or ‘rustling sounds’ people in polar regions talk about.Scientists are still trying to figure out what causes the sound of the northern lights, if indeed they do produce sound and aren’t simply a psychological phenomenon!
Northern lights, or aurora borealis, are glowing shafts of light you see in the night sky.
