Difference between revisions of "Aurora"

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Latest revision as of 20:18, 13 June 2019

The northern lights and southern lights are the common names for an aurora. An aurora is a natural light show seen in the night skies of the Earth's polar regions. The word aurora comes from the Roman goddess of dawn, who was named Aurora. The northern lights are called aurora borealis, aurora for the Roman goddess and borealis after Boreas, the god of the north wind. This is fitting because the aurora is caused by solar winds interacting with the Earth's magnetic field. The southern lights are called aurora australis, australis coming from the Latin word for south.

The most common colour for an aurora is green, although it can be several other colours as well. Red, blue, yellow, and pink are also possible and there is some ultraviolet and infrared light that we cannot see with the naked eye. The aurora also makes a crackling noise that can be heard at 70 meters above the ground.

Causes[edit]

An aurora is caused by solar winds interacting with the Earth's magnetic field (magnetosphere). The exact mechanisms are not fully understood and there are different ideas about how auroras come to be. However, it is clear that the influx of electrons from solar winds into the atmosphere that plays a role. Incoming electrons interact with gases in the atmosphere and give off photons as a result. Photons are basically light particles that then produce the colourful aurora we see in the sky.

History[edit]

Auroras have been recorded since the 4th century BC. The Greek explorer Pytheas wrote that once there was an aurora of such intense red that the fire brigade rode out to the rescue!

For the Australian Aboriginal people, the aurora australis was associated with fire. Some named it puae buae ('ashes') and others believed they were bushfires in the spirit world. Other groups believed it was the result of an evil spirit creating a huge fire or the campfires of spirits in the land of the dead. Still others believed that spirits could communicate with people through the aurora.

Old Norse accounts of norðrljós (aurora borealis) date back to 1230 AD. Norsemen returning from a voyage to Greenland first reported this strange sight and they suggest that it could be caused by fires surrounding the ocean, sun flares, or fluorescent glaciers.

Some Native American people believed that the lights were the spirits of their dead friends dancing in the sky. The brighter the light, the happier the friends.

Other Planets[edit]

  • Jupiter aurora is mostly associated with incoming plasma from its volcanic moon
  • Saturn's aurora is thought to be caused by solar winds, similar to Earth's
  • Auroras have been spotted on Uranus and Neptune
  • Auroras have been seen on Venus, but are caused by a different mechanism. Venus has no magnetic field, so the aurora does not take the same twisting and dancing shapes as the Earth's
  • Mars also has auroras, possibly similar to Earth's