Aurora

Aurora is a natural light display in the sky. It is a luminous phenomenon of Earth’s upper atmosphere that occurs primarily in high latitudes of both hemispheres; auroras in the Northern Hemisphere are called aurora borealis, aurora polaris, or northern lights, and in the Southern Hemisphere aurora australis, or southern lights.

picture: wikipedia

Auroras are caused by the interaction of energetic particles (electrons and protons) of the solar wind with atoms of the upper atmosphere.   Great storms on the sun send gusts of charged solar particles hurtling across space. If Earth is in the path of the particle stream, our planet’s magnetic field and atmosphere react.

When the charged particles from the sun strike atoms and molecules in Earth’s atmosphere, they excite those atoms, causing them to light up. When charged particles from the sun strike atoms in Earth’s atmosphere, electrons move to higher-energy orbits, further away from the nucleus. Then when an electron moves back to a lower-energy orbit, it releases a particle of light or photon.

picture: kafeastronomi

Science says that different gases in Earth’s atmosphere give off different colors when they are excited. Oxygen gives off the green and red colors of the aurora, for example. Nitrogen causes pink and purple colors.

picture: kafeastronomi

Aurora appears in high-latitude areas; Northern hemisphere (Arctic) and Southern hemisphere (Antarctic). In high-latitude areas, the magnetic field is bigger. The best time to see aurora borealis is on March, September, or October in Alaska. In those time, the night sky is darker and the weather is clear. On summer, the night sky is not really dark. On winter, it's really cold for us to see the aurora.

picture: universetoday

There is auroral activity on a large scale in other planets, such as Jupiter, Neptune, Saturn, Uranus, and Jupiter’s moon, Io. This is Jupiter's northern and southern auroras, as observed by the Hubble Space Telescope. The auroras are produced by the interaction of the planet's powerful magnetic field and particles in its upper atmosphere.