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 shape of an aurora depends on the Earth’s magnetic field lines, as the charged particles travel along these lines.
- 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.