Aurora

Wallpaper Description:

An aurora is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere).Most aurorae occur in a band known as the auroral zone[1][2] which is typically 3° to 6° in latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole. During a geomagnetic storm, the auroral zone will expand to lower latitudes. The discrete aurora are sharply defined features within the diffuse aurora which vary in brightness from just barely visible to the naked eye to bright enough to read a newspaper at night. Discrete aurorae are usually observed only in the night sky

In northern latitudes, the effect is known as the aurora borealis (or the northern lights), named after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas, by Pierre Gassendi in 1621.Auroras seen near the magnetic pole may be high overhead, but from farther away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the Sun were rising from an unusual direction. Discrete aurorae often display magnetic field lines or curtain-like structures, and can change within seconds or glow unchanging for hours, most often in fluorescent green. The aurora borealis most often occurs near the equinoxes. The northern lights have had a number of names throughout history. The Cree call this phenomenon the "Dance of the Spirits