What causes the Northern Lights to happen?

The Northern Lights are seen on Earth as spectacular splashes of colour in the night sky.

On Friday experts say amateur star-gazers have the best chance in years of seeing them in all their glory.

The powerful rays can interfere with airline navigation systems, satellites and even NASA space crews.

But if you're wondering what causes the night sky to glow, check out Leah's report from the last time they were really visible to find out more...