Auroras are caused by the interaction between charged particles (such as electrons), ejected from the Sun (solar wind), with the Earth’s magnetosphere.
The magnetosphere accelerates electrons as they enter the atmosphere after travelling from the Sun
The colour and pattern of an aurora are partly determined by the degree of acceleration given to the particles as they enter the atmosphere.
Different gases in Earth’s atmosphere produce different colours of auroras when struck by solar particles. Oxygen produces green and red light, while nitrogen gives blue and purple.
The visibility of auroras depends not only on geographical location and time of day but also on solar activity. Stronger solar winds typically cause more intense auroras.