Bright northern lights dance in the skies above Finland. | Reuters

The northern lights are absolutely stunning and definitely a 'must see' because the beauty of neon shapes blasting across the skies is something you will never, ever forget.

This spectacular light show is caused by electrically charged particles from space entering the Earth's upper atmosphere at a very high speed. A small percentage of particles leak through the Earth's magnetic field and are funnelled downwards towards the North and South poles.

This week there's been quite a show in the skies over Finland with bright green, white and grey lights flashing up above and leaving people speechless.

Video of the aurora borealis in Finland has been uploaded to social media platforms and it’s really worth a look, especially around 43 minutes in, when the colours are really intense.

The northern lights are very unpredictable, but the best time to see them is during the dark, clear night skies between December and March and the closer you are to the Arctic Circle, in places like Alaska, Canada, Iceland, Greenland, Norway, Sweden and Finland the better, especially around the time of a new moon.

Here's a selection of photos uploaded to Twitter on Monday and according to weather experts there's an even more spectacular show in store on Tuesday night, especially in Scotland.