What is an aurora?

Have you ever heard of the Aurora Borealis and the Autorar Australis? What exactly are these amazingly beautiful lights in the sky?

An aurora, sometimes referred to as a polar light or northern light, is a natural light display in the sky. They can be seen predominantly in the high latitude (Arctic and Antarctic) regions.

Auroras are produced when the magnetosphere is sufficiently disturbed by the solar wind that the trajectories of charged particles in both solar wind and magnetospheric plasma (mainly electrons and protons) precipitate them into the upper atmosphere, where their energy is lost.

The resulting ionization and excitation of atmospheric constituents emits light of varying colour and complexity.

In simpler terms: the bright dancing lights of the aurora are actually collisions between electrically charged particles from the sun that enter the earth’s atmosphere.

Auroras frequently appears either as a diffuse glow or as “curtains” that extend approximately in the east-west direction. At some times, they form “quiet arcs”; at others they evolve and change constantly. These are known as “active aurora”.

Auroras can come in different colours, which vary depending on the conditions and different altitudes where they occur. They can be red, green, blue and even ultraviolet or infrared – which can only be seen with the appropriate equipment.

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Auroras can also produce noise. The sound, similar to a hissing, or crackling noise, begins approximately 70 meters (230 feet) above the Earth’s surface and is caused by charged particles in an inversion layer of the atmosphere formed during a cold night. The charged particles discharge when particles from the Sun hit the inversion layer creating the noise.

To learn more about this fascinating and mesmerizing natural phenomenon watch the following TED-Ed video:

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