Getting to see the majestic northern lights is a bucket list experience for many, but unfortunately, the lights are as uncontrollable as the weather. But if you are lucky enough to catch them at the perfect time, it is a memory that can last a lifetime. 

Polar lights, also known as aurora polaris or just aurora, usually occur around the north and south poles of our planet, which have gotten the scientific names aurora borealis and aurora australis respectively. Though rare, powerful polar lights can reach greater areas of the planet, and polar lights have even been spotted in regions around the Equator. 

The natural phenomenon of the aurora has awakened both wander and fear since the beginning of humanity. There are countless legends and myths about what the lights mean; from stories about battles between good and evil celestial dragons, a firefox running across the snow causing sparks to fly up in the air and spirits trying to communicate with loved ones - or just playing ball - to beliefs as to how the lights affects life, and particularly birth, with some believing the lights would bless a child with good looks, intellect and good fortune while others fearing children born under the aurora would be stillborn or die during birth. It’s safe to say that the polar lights have been something humans have respected, whether it be with celebrations or fear. 

But what are the polar lights exactly?

The source of the polar lights is, as with many other natural phenomenons, the Sun. The active star continuously throws solar winds out into the universe in all directions, and some of these winds are directed towards our Earth. This happens all the time, and is generally not something we even notice, as most solar winds never make it inside our atmosphere. However, when something called a coronal mass ejection, or in other words, a massive eruption on the Sun’s surface occurs, the solar winds thrown towards Earth are powerful enough that some of the electromagnetic matter disturbs Earth’s magnetic field and escapes through to our atmosphere. The electromagnetic particles from the sun are drawn towards the poles where they collide with atoms and molecules from the gasses in our atmosphere. This collision causes the atoms and molecules to emit photon energy in the form of light, which is what we can see as the dancing polar lights in the sky.

/ Image: the Norwegian Centre for Space Weather

Northern lights, specifically, are commonly known as green lights across the sky, but there can be slight colour variations depending on where the solar particles collide with atoms and molecules in our atmosphere. The aurora occurs at around 80 to 250 km above ground, and the height is part of what determines the colour you and I see. The majority of the aurora usually occurs at approximately 100 - 200 km above ground, where the sun particles collide with oxygen molecules which emits different shades of green lights. Towards the upper edge of the aurora, the oxygen emits a red colour which may also be spotted at times, and at the lover edge, where the sun particles mostly collide with nitrogen, the light photons take the shade of purple.

Another reason as to why we know the northern lights as predominantly green, is because the human eye catches green more easily, and a camera can therefore usually pick up more colour variations in the aurora than what we can see with our own eyes. 

/ Image: the Norwegian Centre for Space Weather

The light show most commonly occurs around the belts called aurora ovals, which are located around both the north and south geomagnetic poles, though extra powerful solar winds can make the aurora visible over a greater area of the planet. The northern aurora oval covers places such as northern Scandinavia, Finland and Russia, as well as Iceland, Greenland, Canada, and the state of Alaska, which are all great places to view the beautiful show, while the southern lights can mostly be seen from Tasmania, the south of New Zealand and Antarctica. As these belts stretch around the earth, over both night and day, aurorae can happen at any time. However, daytime aurora cannot be spotted by the naked eye, unless you are located within the polar circle at winter time when it is dark even during the day. Though it exists, daytime aurora is still not as strong as the dance that occurs during nighttime, which is why the polar lights are typically known as a phenomenon in the night sky. 

The aurora is most visible during the winter, when the night sky is darkest, and can most commonly be seen between September and March. The ideal time of day to view the magnificent lights is at what is called the magnetic midnight, which is when the north or south magnetic pole, not to be confused with the geographical poles (see image below), is in alignment with the Sun and the observer on Earth’s surface, and this usually occurs about an hour before conventional midnight. But you can still see spectacular auroras at any time during the dark hours of the night. Also to keep in mind if you want to get the best experience possible is that the lights are above cloud level, so a cloudless night helps, and it is a good idea to try to get as far away from any big cities as possible, as the light pollution can ruin the view. Additionally, if you are lucky enough to observe the aurora during a full moon, you may notice that the lights appear sharper in any photos you take!

/ Image: BBC Sky at Night Magazine

Something you may not have thought of before, is the aurora is not unique to Earth. Other planets in our solar system have also been photographed with similar light shows circling their poles, for example the two largest planets Jupiter and Saturn. Any planet with the right conditions, having a sufficiently dense atmosphere being one of such, can have aurorae, and this even goes for some planets’ moons!

Nowadays scientists know a lot about how and why the auroras occur, but according to the Norwegian Centre for Space Weather there are still some aspects of the dancing lights that remain a mystery.