Before we dive into understanding “what are the northern lights” it is important to point out a couple of facts about the space surrounding our Earth. These are mainly things we can´t see with our eyes. One of these things are the air we breath. It is in fact a mixture of several gases – mainly nitrogen and oxygen, but with some traces of hydrogen, helium and some other minor compounds.
What are the northern lights?: The earth as a field of magnet
Another thing we can´t see is the magnetic field that surrounds the Earth. In similar manner as if you have played with a bar magnet and iron filing you have seen how it forms the curved patterns in the magnetic field. The magnet is actually deep in the core of the Earth. As we cant see the magnetic field we normally represent it by drawing lines. Lines that go into and out of the Earth where the poles are. When the lines area closer the field is stronger.