Many people know what the aurora is.
It’s those lights in the sky!
The Aurora Borealis, which is the northern hemisphere version, gets the most coverage. Although this is changing and a lot more people are beginning to realise that it can also be seen in the southern part of the world. The southern most southern parts of the world that is. Such as Tasmania, the south island of New Zealand, and the southern most parts of South America. Which has the nickname of the Aurora Australis
Recently I had some friends visiting, and Evan, a very inquisitive ‘almost eight year old’, asked to see some of my photos. He also wanted to know a bit more about the aurora and, of course, the favourite question of all small humans ‘why’. I decided to try my hand at explaining and aurora in such a way that an ‘almost eight year old’ could understand and enjoy.
It all begins with the sun and the energy it spits out from time to time. Being so hot up there, it occasionally bubbles away and just like when the boiling water spits out of the top of the pasta pot, sometimes the sun can spit out some plasma particles. Instead of these particles just floating off into the vast expanse of space, if they are pointing toward Earth, they come hurtling toward it. Considering the sun is a long way from Earth (149.6 million kms) it can take a day or two for these particles to reach us. We call these particles solar wind, so when you next hear me talk about solar wind, you know it is the spit particles from the sun.
Once the particles get to earth they run into our magnetosphere, which is the magnetic field around earth. This field keeps us safe from the harmful rays and particles which are bouncing around in the universe. I guess we can kind of think of it as a force field, that stops the bad cosmic rays from frying us. Thanks magnetosphere for keeping us alive. Not only keeping us safe, it is this magnetic field which give us Auroras!
But how…?
We now know about the sun, spitting out particles (solar wind) and the magnetic field around the Earth keeping us safe. Put these two together, and add a few other ingredients, and you end up with lights shooting up and across the sky at the ends of the Earth.
When the solar wind collides with the magnetic field, bits of the wind can get through. When they are through they crash into a whole bunch of different atoms and molecules in the atmosphere. Usually these atoms and molecules are just hanging out, doing what they do, helping us breathe and stuff. But when they get hit with a bit of solar wind they get all excited. Excited atoms and molecules bounce around really quickly and all over the place and start shooting out photons. Photons are little packets of energy that show themselves as light. So lots of photons from excited atoms and molecules makes an amazing light show in the sky!
The different colours that you can see in an Aurora are made by the different atoms and molecules. The different colour combinations depend on the amount oxygen and nitrogen in the atmosphere, and also at what distance above earth they are the thickest (their altitude). Usually you will see greens toward the bottom and reds higher up.
Not all auroras are the same… There are loads of different shapes and patterns you can see. Arcs, bands, curtains, picket fences, veils, patches and rays. Although we aren’t totally sure what causes this.
What your eyes see…
Unfortunately, what you see in all the amazing photos of auroras, isn’t what you will see with your own eyeballs. Some people have seen some colour, especially when they are right up at the north pole or down in Antarctica. Most of us though are lucky to be able to see the white shapes of the light. To have a higher chance of seeing it with your eyes, it needs to be dark, you need to be in a location facing south, and there needs to be very little light pollution. Preferably no light pollution at all, especially the way you are facing. These things are ones you can control. What you also need is a fairly strong aurora.
Quite often you will see a low band on the horizon of white light. It kind of looks like the glow from a city in the far distance. Assuming there is no city in the distance, then you will be seeing the aurora. Occasionally you may see beams of light shooting upwards, fading in and out and moving about the sky. This isn’t as common though.
The best way to take full advantage of the aurora is to get yourself a camera that you can adjust the shutter speed on, and take a long exposure. Your eyes aren’t as sensitive as a camera sensor and can’t pick up the vast array of colours which are there. Many people think that aurora photos are ‘photoshopped’ or drawn on and coloured in. They aren’t, it is simply the view from a more sensitive bit of optical equipment.
Having said that, if there is a big aurora going on, it is worth popping out to a dark place and having a look. I have seen a few really strong auroras with my eyes (not just in camera) and holy moly it is an amazing experience!
When is the best time to see an aurora…
There are a few groups and pages on facebook which have members who post about possible aurora predictions. You can search those out and join up. It’s a lot like the weather really, although on a shorter time frame. There are lots of satellites which measure all the things going on space, and they can give a good idea when the sun is going to start spitting out solar wind. Remember though, it is just a prediction! There isn’t a best time of the year, or a best time of the night, well not that we know about anyway. Although, in winter you have a higher chance of seeing one. Solely due to the fact that there is more night time hours in winter, so you can go out a bit earlier and be home at a reasonable time.
Another thing that can effect the occurrence of auroras is the suns 11 year solar cycle. Typically it takes about five and a half years for the sun to go from maximum solar activity back to minimum. Eleven years to do the full cycle. The higher the activity, the more the sun spits out particles, which means it is a lot more likely for an aurora to happen. When the sun is at its minimum, and its activity is lower, then so is the chance of auroras. This doesn’t mean there won’t be any auroras, it just means there probably won’t be so many. At the moment, we are just hitting the solar minimum. Bummer.
About the photos
All the photos contained here are ones I have taken. I went through a stage of being obsessed with photographing the aurora. My friend Leena and I used to go out, on average, five nights a week. We would sit under the stars in the freezing cold, or warm summer nights and watch and wait. Quite often an aurora would pop up even if there wasn’t a prediction, so we thought it best to be there just in case. We don’t go out as much as we used to. Sometimes i wonder how we burned the candle at both ends for so long! Perhaps this winter I might head out a bit more…
