What creates the aurora on Mars?

There are three things you need to create an aurora on a planet: 1) A lot of charged subatomic particles moving rapidly, like those continuously blown away from the Sun in its solar wind; 2) a magnetic field, which funnels the particles downward and concentrates them; and 3) an atmosphere filled with fun atoms and molecules that glow brilliantly when struck by a fast moving charged subatomic particle funneled by a magnetic field.