If you live in Scotland or the North of England and were lucky enough to have clear skies last night, you may have been able to see one of Physics’ greatest natural shows – the aurora.

Normally you need to go to a place like Northern Norway to see this phenomena, but with the recent increase in solar activity and a massive coronal mass ejection from the surface of the Sun on Monday morning, the Northern aurora (or Aurora borealis) have been visible far further South (as long as you look near the Northern horizon).

But what causes the aurora?  Thought once to be spirits in the sky, aurora are actually a product of physics in action.  The Northern Lights are actually the result of collisions between gaseous particles in the Earth's atmosphere with high speed charged particles released from the Sun's atmosphere. The usual green colour is given when oxygen atoms become excited by these charged particles.  An oxygen electron needs to lose energy so that the atom can return to its normal state, and it does this by emitting a small packet of energy called a photon of a specific wavelength – that of green light.  Other colours can also be seen at times – usually caused by excited nitrogen returning to its ground state emitting blue or red photons.

But why do we see them at the poles?  Well the Earth is protected from this harmful solar wind by our magnetic field.  Charged particles from the Sun however can become trapped in this field, and get funnelled down towards the poles.  It just so happens that with yesterdays geomagnetic storm caused by the large coronal mass ejection that this ‘funnel’ became wider, allowing the aurora to be seen further South.

And it is not over yet, with solar activity continuing to increase, we will have more events to come, so check back with the National Space Centre to keep up to date with these breathtaking lights in the sky.