what is the Aurora Borealis and what causes them?

Answer 1

Good ole Wiki can answer that:

Answer 2

It's what is commonly called "Northern Lights". This is a result of a solar flare or solar storm blasted off the surface of the sun in the earths direction. Once the electrons make it to our atmosphere, it causes the colorful dancing lights. If there is a solar storm that is substantial, it not only gives us a great show, but can cause havoc with all of our electrical systems (caused a massive blackout in Canada in recent memory).