Magnetosphere & aurora

Magnetosphere & aurora
It is because we have a magnetosphere that our planet has the spectacular aurora borealis and australis - the northern and southern lights that can often be seen at night near the arctic and antarctic circles. The aurora are caused by electrons from the magnetosphere being accelerated along the Earth's magnetic field into the upper atmosphere, where they collide with atmospheric particles at altitudes between 100 and 200km. The brightest color of aurora, green is caused by electrons hitting oxygen atoms in the atmosphere.

Images from space have shown us that the aurora form ovals centered around Earth's magnetic poles. The radius of these ovals get larger and the aurora move to lower latitudes when the Earth's magnetosphere is strongly affected by the solar wind or engulfed by a coronal mass ejection, a massive explosion of solar plasma and magnetic field that travels through the solar system, often at speeds much faster than the normal solar wind. 

Explanation via UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS
http://www.ucl.ac.uk/mssl/space-plasma-physics/plasma-science/aurora

Read & Learn:
http://www.atoptics.co.uk/highsky/auror2.htm

Animation:
solar wind impacting the magnetosphere and creating aurora
Animation credit SOHO

#magnetosphere   #aurora   #CME   #SOHO   #universe   #space