The results are in from last weeks poll. Showing a preference for ‘Stunning Saturday’ and ‘Simple Sunday’. For the moment I will post both series, however future time restraints may restrict me to just doing one, for which I will pick the most popular! As always I would love to hear your thoughts and suggestions for anything you would like me to cover.
So, Welcome to the very first episode of ‘Stunning Saturday’ where I shall bring you some of the most beautifully stunning events and phenomena that occur in our Universe.
I think a very good place to start is with something that is on my personal bucket list and I can imagine millions of people around the world yearn to also see this with their own eyes. It is of course the Northern lights (Aurora Borealis). Even just saying the name conjures up awe-inspiring images in my mind, it is a purely ethereal display.
The first I’d ever heard of the northern lights was whilst reading ‘His dark materials’ trilogy by Philip Pullman as a kid, the northern lights has been referenced in science fiction, mythology and folklore many, many times. The Fins interpretation of them is a magical fox sweeping his tail across the snow spraying it into the sky. In Norwegian folklore the lights are the spirits of old maids dancing in the sky, and in Scotland they are known as the ‘merry dancers of the sky’. While the Lapps believe these ‘fires’ have calming effects on conflicts and there are also theories that the northern lights are the spirits of ancient heroes battling in the night sky.
Most of us have probably seen pictures or videos of the dancing pale greens and the shimmering pink sheets with the odd dash of yellows, reds, blues and violet thrown in for good measure. Some of you reading this may have even been lucky enough to see them for yourself (for which I am truly jealous! Ha).
But what actually is the northern lights, and what causes it? Well, simply put the bright dancing lights are caused by collisions between electrically charged particles from the sun that enter the earth’s atmosphere.
A solar flare is a sudden flash of brightness on the suns surface. They are caused by magnetic reconnection, where magnetic energy is converted to kinetic energy (energy an object possesses due to its movement), thermal energy (heat) and particle acceleration. This rapid acceleration of particles causes closely linked loops of magnetic lines that are unconnected to the rest of the solar magnetic field and expand outwards. This is also why solar flares tend to occur in areas of the sun with much stronger magnetic fields. These flares result in a huge ejection of electrons, ions and atoms (charged particles) into space, typically reaching the Earth a day or two later.
When these charged particles reach Earth’s atmosphere they collide with the molecules in the Earth’s atmosphere and excite them. To explain the excitation of an atom, simply imagine a hyper child, where they reach an energy level that is above their normal level (or ground state), in the case of particles it is the surrounding cloud of electrons that move to a higher energy state. Of course this molecule (or child) cannot maintain this energy level for long. To return back to an energy level it is happy with it must eject this extra energy in the form of a photon (a light particle), I guess that is where the hyper child analogy ends….
Why is this light emission different colours? Well, when the photon is released it will have a certain amount of energy, which is different relative to the amount the molecule was ‘excited’. The varying energy of emitted photons leads to an array of colours or the electromagnetic spectrum.
But why does this tend to only occur in the north? This is a result of our magnetic field ‘directing’ the suns particles towards the magnetic North pole. The Northern lights are therefore most often seen in countries such as; Canada, Alaska, Scandinavia, Finland, Iceland, Greenland and occasionally Scotland. There is also the counter part to the Northern lights, which occur at Earth’s Southern magnetic pole and is known as Aurora Australis.
So there we have it, a VERY brief explanation of, what I think at least, one of the most beautiful natural phenomena to occur on Earth (or about 100 Km above it).