Auroral arcs

Auroras form in high latitude regions of Earth, and appear in many different shapes. The aurora in the early evening sky forms a green arc that stretches across the sky in an east-west direction. The longitudinal extent (length) of an auroral arc can be as large as several thousands kilometres, but its width can be as small as 100 metres.

The deep mechanisms that rule the creation of such beutiful natural light displays (also called polar lights), have been the subject of studies that are keeping solar and plasma scientists busy since years.