It is many people’s wish and dream to one day see the Northern Lights. They are, after all, a wonder of nature that have captivated people for centuries. These lights, also occurring in the south of the planet, are not only beautiful, they are also a connection between us and space beyond our little planet, as well as for some people being connections between time and worlds. In this plog we will be looking at what causes the northern and southern lights, as well as some of the folklore surrounding them. Hope you enjoy!
What they are
The northern lights, also known as aurora borealis, and southern lights known as aurora australis are, quite frankly, stunning. They are incredible light shows in the sky, constantly moving and ranging from a pale white to the most common green to a rarer pink and purple. Sometimes they look like arcs in the sky, sometimes moving bands like curtains, and sometimes they appear as rays shooting up into the sky straight above you. How are these lights created? For that, we need to head out into space.
The sun is constantly emitting what are known as solar winds- streams of electrically charged particles like protons and electrons which are coming out of our sun in all directions. Earth however, is surrounded by a magnetic field which deflects most of these particles. This causes a sort of dent in the sun’s solar winds where the earth is and in the area just behind it where it is protected. I say just behind it, this protected area, the magnetosphere, goes from the tip of our protective sphere 60,000 km towards the sun, to many hundreds of thousands of kilometres behind us.
The energy that does get in is stored temporarily within the magnetosphere above the earth’s atmosphere. However, if too much energy comes in at once, the magnetosphere gets knocked slightly out of balance and sort of re-balances by releasing energy. This energy, in the form of electrons, is guided around the earth to where the magnetosphere stops going around the planet and starts tailing off behind it, this happening to be the near North and South poles. So there are special energy particles there but, how does that give us lights??
What makes the lights
When these electrons end up near the poles, many of them fly into our atmosphere. Though we often think of the atmosphere as pretty empty, it does contain some gas molecules like oxygen and nitrogen. When the fast moving electrons slam into these gas molecules, they transfer the energy to them. At first, the molecules are ‘excited’m full of this energy, but then they slowly start to release this energy in the form of light and hey presto, you’ve got aurora!
The more energy provided by the solar winds, the more electrons come flying through the atmosphere, and so the more bright and fast moving the lights are. This all goes on at around 100-400 km above our planets surface.
The colour of the aurora depends on what molecules are being hit the most by the electrons, as well as how ‘excited’ they are getting. High energy electrons cause green lights to come when they hit oxygen, whilst low energy electrons cause reddish lights. When more nitrogen molecules are hit this causes blue light, which when combined with the oxygen can cause the purples, pinks and whites. There are also lots of colours being emitted which are beyond our ability to see, but which can be picked up by machines as ultraviolet light.
The lights don’t actually occur right on the poles, but a bit further towards the equator, and as the earth is constantly rotating this means that the band where they happen is a ring. In the north this is over Alaska, Canada, Scandinavia, Northern Russia and Greenland, though it can shift north and south sometimes, and in the south the ring of lights is mostly above Antarctica though can move as far north as to be seen in southern Chile, Australia and New Zealand.
How to see them, and what can they do
Normally there is some low level lights going on all the time. In daytime we can’t see them as the light from the sun is much more powerful so it covers it up. In many places now they can’t be seen at night either because of light pollution from towns and cities. Generally the best time to see the aurora is a few hours before midnight in a place undisturbed by light pollution, or even on a plane ride at night. They aren’t especially around more during wintertime, it is just that we have more hours of darkness then so are more likely to see them. Jupiter, Saturn and Uranus also get auroras, thought we haven’t seen traces of them on other planets.
These lights aren’t just pretty however, they actually have an effect on us. As they are the result of surges of energy in our atmosphere, they can affect our electrical systems, causing unexpected currents to run through electricity lines and communication lines causing power outages and disrupting communication. They can also cause radio signals to bend in unusual ways reducing or absorbing them, and can alter satellites sometimes even causing them to send false commands through damaged electronics.
The beauty and ethereal quality of the aurora mean that they have been noticed by people for thousands of years before they started tweaking our tech. As they were so mysterious, there are many folktales about what they are. Here is just a small sample from the beautiful to the scary:
Ngarrindjeri people of South Australia thought that the aurora were the campfires of the ancestors in the ‘Land of the Dead’, whilst the Dieri people in the south of the continent believed the aurora was kootchee, an evil spirit creating a large fire. A Norse chronicler from 1200s A.D on hearing about these strange lights in Greenland thought that they must be either vast fires surrounding the ocean, that the light of the sun could reach around the earth to its ‘night side’, or that glaciers in Greenland could store energy and release it as light.
The Chipewyan Dene in North America thought that the lights were the dancing spirits of those who had passed on, and when they shone very brightly this meant that the spirits of those departed were especially happy.
Various Inuit groups have a tale that the Northern Lights are the spirits playing a game of football with the skull of a walrus, though the Inuit in Nunivak, Canada interpret it slightly darker as walrus spirits playing with the skull of a human. Continuing on the darker note the Mandan people in North Dakota thought that the lights were great medicine men and warriors with enormous simmering pots containing their dead enemies. In Finland the story goes that an Arctic Fox is running in the far north and when its tail sweeps the snow upwards this creates the lights.
Whether seen as the souls of the departed, violent flames, or simply beautiful sights, the Northern and Southern Lights have captivated us humans for centuries. Not only are they beautiful and ethereal, but they also remind us about our connection to the things outside our planet like the solar winds of the sun and the invisible particles flowing around and through us daily, which in itself is pretty incredible. Not only does the sun give us light and energy during the day, but it reflects its light off the moon to us at night and in some places even gives us beautiful light shows!
For more info:
Here’s a nice timelapse video of some beautiful northern lights
Cover image: US Air Force/Public Domain