Explanation Text

Aurora
An aurora (plural aurorae/auroras) is an electro-static phenomenon, characterised by a bright glow and caused by the collision of charged particles in the magnetosphere with atoms in the Earth’s upper atmosphere.


Ultimately, the source lies in the solar wind, a fast-moving stream of particles constantly flowing from the Sun that carries the Sun’s magnetic field out into space. The solar wind, typically moving at 250 miles (400 kilometers) per second, flows past Earth’s magnetic field and molds it into an elongated bubble or cavity, compressing its sunward side and stretching its night side far beyond the Moon’s orbit. Under certain conditions, the solar wind’s magnetic field can merge with Earth’s, creating electrical currents that drive protons and electrons into the polar atmosphere. Powerful events occurring on the Sun can drive enormous changes in the solar wind, increasing both its speed and density and enhancing its effect on Earth.

An aurora is usually observed in the night sky, particularly in the polar zone. For this latter reason, some scientists call it a “polar aurora” (or “aurora polaris”).

Aurora Coloured light in the night sky near the Earth’s magnetic poles, called aurora borealis (‘northern lights’) in the northern hemisphere and aurora australis (‘southern lights’) in the southern hemisphere.






Northern lights is the name of a light phenomenon often seen in the northern regions. The lights have been around since Earth formed an atmosphere The scientific name for the phenomenon is “Aurora Borealis”, aurora for short.








The southern lights or aurora australis, most commonly seen in southern New Zealand. It shows a typical red and green aurora, the nearly vertical rays tracing the earth’s magnetic field lines.


source : http://digitalphotopix.com/photo-gallery/what-is-aurora/