The arrival of the solar maximum means more powerful aurora borealis activity. Astronomer Tom Kerss explains the science behind the cosmic phenomenon...
If you're someone who's always dreamed of seeing the dancing colours of the northern lights, then 2024 is the year to make that dream a reality.
Occurring every 11 years, the solar maximum is said to create the most spectacular aurora borealis displays. The next maximum is set to peak in 2024/2025, meaning the seasons of winter and autumn will be the best time to finally book that trip of a lifetime.
Here, author, aurora-chaser and astronomer Tom Kerss tells us exactly what the solar maximum is, how it impacts the northern lights, plus his top tips for seeing them and the science behind the colours.
Northern lights over Tromsø, Norway (Shutterstock)
We don’t often think about the sun changing, but the sun is changing all the time. It has a heartbeat of sorts that takes about five minutes, and we can listen to that wave passing through the sun. It also changes in brightness a little. But one of the most evident changes on the sun is that, if we use a special telescope to look at the sun and filter the sun's light down many times so it's safe to look at, we notice there are these dark marks on the sun.
Galileo was one of the first people to study these marks on the sun, and that was over 400 years ago. Very quickly after these sunspots were first discovered, astronomers noticed that sometimes there were a lot of spots on the sun, and sometimes there were no spots on the sun. They started to also notice a cycle, where every 11 years there would be a maximum number of spots on the sun, and then in the intervening periods, also on a cycle of 11 years, there would be a minimum number of sunspots, which might mean that you have two months where not a single spot is visible.
This solar cycle tells us something about the inside of the sun and its magnetic field. When we have the maximum number of sunspots, we call that the solar maximum.
It’s around that time when the sun has the maximum number of sunspots that the probability of seeing very good displays of the northern lights goes much higher. As a result, for aurora chasers, we really like to think about the solar maximum as a great time to go and see the northern lights. Particularly if you want to have those displays that people talk about for decades. Those real, once-in-a-lifetime memories that are so exciting.
We predict that the solar maximum is going to arrive this year in 2024. Exactly when it arrives, we can't know for sure, because we won't know when the solar maximum happens until after it's passed. Only by looking backwards will we be able to say exactly when it arrived. But what we can say is that in this period of time, sightings of the northern lights are likely to reach their maximum intensity and frequency.
How long will it last? We also don’t know. It could be that we get a long maximum and that it stretches out over years. Some of the models we have are predicting that may happen, and for aurora chasers, that's very exciting.
Green is the prominent colour of the northern lights, but there's also displays with purple too (Hurtigruten/Tom Kerss)
A strong aurora display, captured by Tom (Hurtigruten/Tom Kerss)
The visibility of the northern lights sort of depends on factors that you can and can’t control.
We need dark nights for the northern lights to become visible. It's a bit of a myth, but the northern lights don't just come out and appear. They’re there all the time, but they change with intensity.
We would normally expect the aurora season to start in September and to end in March. It is possible in late August, sometimes, if there's very strong displays, and it can be possible in early April as well. If you want long nights of darkness, then going between November and February are the ultimate times to go.
During the solar maximum, the visibility of the auroras can only be extended a little bit. What the maximum brings us is more intense displays of auroras at a higher frequency.
Consider travelling as part of your itinerary, for example on an expedition cruise. Visiting different destinations increases your chances of finding them and is also a great way of changing up the landscape to make even more memories.
In terms of actually seeing the lights, my number one tip is perseverance. You want to give yourself a few hours and make aurora spotting part of your routine, so that you are thinking about it every evening and giving it some extended attention. Because you might be under some cloud for a while, but after an hour that cloud could break. It might break for just a few minutes, and you don't want to miss that.
My final tip is to think about northern lights etiquette. Maintain dark conditions as much as possible. Think about getting a torch with a red light because that keeps it a little bit darker. Make sure all your phone and camera screens are turned down to their minimum brightness. When your eyes are well adapted to the dark, that’s when the real magic happens. You will be able to see the faintest auroras and the different colours of the northern lights.
The colours of the northern lights are something we like to say are mysterious, but we do understand well. Essentially the colours are emitted by the different gases in our atmosphere.
The oxygen atoms in our atmosphere emit a green light, the most prominent colour. It's also the colour that’s most visible for our eyes.
Pink is a colour you can see during very powerful aurora displays. It’s the lowest down in the aurora and it's released by nitrogen, which is the most common gas in our atmosphere. We often think oxygen is, but nitrogen is much more common.
There’s also the possibility to see purple lights, particularly in photographs. That's a mixture of nitrogen and oxygen.
The exotic red light occurs right at the top of the aurora curtains. It's released by oxygen, but the electrons are doing a slightly different thing than when they're lower down and we see the green colours. It’s difficult to see by eye unless the aurora is very powerful.
Tom Kerss is the author of Northern Lights: The Definitive Guide to Auroras and also one of Hurtigruten's resident astronomers. Follow him on Twitter.
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