Aurora

Aurora (also known as the polar lights) are natural displays featuring curtains, rays, spirals, and flickering patterns of light in the northern polar latitudes (Aurora Borealis) and southern polar latitudes (Aurora Australis). They are most prominent after dark.

  • Auroras are caused by the interaction of 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.
Related diagrams

Each diagram below can be viewed on its own page with a full explanation.

References