Why are aurora always in the vicinity of Earth's poles?

[al33]

Why aurora happen near north or south pole more easily? I mean why charged particles can escape the Van Allen belts more easily to have collisions with particles in the atmosphere? Why are they harder to escape near equator? Isn't it supposed to have weaker magnetic field near the equator?

 

[anorlunda]

Does that picture help answer your question?

 

[davenn]

Why aurora happen near north or south pole more easily? I mean why charged particles can escape the Van Allen belts more easily to have collisions with particles in the atmosphere? Why are they harder to escape near equator? Isn't it supposed to have weaker magnetic field near the equator?

To take Anorlundas' reply a bit further ...

The Earth's magnetic field lines enter/exit the north and south magnetic poles. The aurorae are caused by charged particles, mainly electrons and protons, that get trapped in the magnetic field and they spiral down the field lines to each of the two poles where they collide/interact with oxygey and nitrogen atoms in the upper atmosphere causing the auroral glow

As a result you can only get aurorae in the polar - high latitude regionscheers
Dave