A huge solar flare sent a wave of particles out through space and people around the world enjoyed the view. The Aurora was seen as far south as Hawaii in the north and as far south as Mackay in the south over the weekend. The peak of the sunspot cycle is approaching, and periods of intenseAurora are likely to return over the next year or so. You might be wondering what the glow and different colors of the sky are all about.
During times of heightened solar activity, there are more charged particles smashing into Earth's atmosphere. The charged particles can sneak in near the poles and wreak havoc, even though most of the atmosphere is protected. The upper atmosphere has 20% oxygen and 80% nitrogen, with a trace amount of water, carbon dioxide and argon. The oxygen atoms generated by the sun are excited and can produce ozone, a molecule that protects us from harmful UV radiation. The green light is caused by the atoms' electrons being rearranged in an unstable way. The rules of quantum mechanics allow these emissions to happen very quickly. A yellow–orange photon is released when a sodium atom is in an excited state. Nature finds a way, despite the fact that many of the oxygen atoms are created in excited states.
The process of relaxing oxygen atoms in a state of 1S to a state of 1D takes almost a whole second. This transition is very slow because the excited atom will have lost energy by bumping into another atom before it has a chance to send out a photon. They have a chance to release a photon in the upper reaches of the atmosphere, where there is less oxygen in the air. It took scientists a long time to figure out that the green light came from oxygen atoms. It wasn't until the 1920s that Canadian scientists figured out the cause of the red light. The green light comes from a transition where an electron in the oxygen atom jumps from one pattern to another. The oxygen atom is in another excited state after emitting that green photon. The 1D state has to survive for about two minutes before it can break the rules and give off red light. The red light only appears at high altitudes, where there are very few atoms and molecules. The red light appears above the green because there is a small amount of oxygen up there. The red light is emitted more slowly and has a higher chance of being extinguished by other atoms than the other way around.
Green and red are the most popular colors, but there are other colors as well. There are two reasons for this, the first of which is that they show up more in the camera lens. First, cameras have the advantage of a long exposure, which means they can spend more time collecting light to produce an image than our eyes can. We tend to see in black and white in low light, because the colour sensors in our eyes don't work well in the dark. The naked eye can see the colors of the Aurora when it is bright.