collision of charged particles

Why would the sky look like a giant fan? None other than airglow of course! The featured intermittent green glow appeared to rise from a lake through the arch of our Milky Way Galaxy, as captured last summer next to Bryce Canyon in Utah, USA. The unusual pattern was created by atmospheric gravity waves, ripples of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up.

Now, unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark.

Image Credit & Copyright: Dave Lane; Rollover Annotation: Judy Schmidt

A long time ago, when our ancestors admired the beauty of the Northern and Southern Lights, they thought the lights were spirits or souls dancing in the sky. Sometimes the lights were believed to be Gods or Goddesses appearing to mortals. The Northern and Southern Lights caused a range of emotions in the people who witnessed then - alarm, fear, wonder, dread and excitement.  People did not understand what caused these amazing spectacles of lights in the sky. The phenomena of the Northern Lights were explained by different stories.  Today we know that the 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.The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth’s magnetic field into the atmosphere.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.

 Image credit: Gunnar Þór Gunnarsson /My edit