How are auroras formed?
1 Answer
Aurora are formed from the solar wind interacting with the Earth's magnetosphere and atmosphere.
Explanation:
The solar wind is a stream of particles coming from the sun. When these particles interact with the Earth's magnetosphere, some particles are deflected into the atmosphere near the poles. The particles, which are mainly protons and electrons, ionise the atmospheric gases. When the gasses return to their ground state they emit light which are the aurora.
The predominant colour of aurora is green. This is caused by the ionisation of oxygen. Other colours such as reds and purples can also occur due to other ionisation states of oxygen and ionisation of nitrogen.
Auroras are normally only visible in the high latitudes. When the sun has magnetic storms the particle flow greatly increases and the aurora are brighter and visible at lower latitudes.
The best time to see the aurora is around the equinoxes around local midnight. You need to go to a place without light pollution between 2300 and 0200.
This photograph was taken near Akureyri, Iceland in March 2015.
