Archive for November 28th, 2009

The Aurora


A different Aurora.

[*This is an article I wrote for a class in response to an incorrect article in a local newspaper*]
The winter season brings with it more viewings of the Aurora Borealis or more commonly the Northern Lights. Sheets of red, blues and greens dance in the skies of far northern (and southern) latitudes. While it is commonly thought that the aurora is more prevalent during the winter it is in fact constantly active throughout the year. Winter months just provide longer nights in which to view the aurora.
The Aurora is caused by the interaction of energetic particles with the Earth’s ionosphere. These particles come from interactions within the magnetosphere of the Earth. The magnetosphere is the space created by the interaction of the Earth’s innate magnetic field (which we use for compasses) and the solar wind. The solar wind is a consistent flow of particles in the form of plasma that have blown off the surface of the sun.
When the solar wind reaches the magnetosphere of the earth a bow shock, similar to a boat, forms on the sun side of the planet. This deforms the magnetosphere into the shape of an elongated tear drop. In the stretched out tail of the magnetosphere the magnetic fields get stretched out and oppositely direction fields get closer together. These opposite fields can collapse together and send particles streaming back towards the earth.
These streaming particles then approach the upper reaches of the atmosphere where they are accelerated to high energies. As they zoom into the atmosphere they interact with the ambient particles and molecules, giving away their energy as they slow down. The now excited oxygen and nitrogen give off the characteristic red, green and blue lights that we see as the Aurora.
The current location of the auroral oval can be seen at spaceweather.com along with more information about the current space weather conditions. For more in-depth information on the physics of the aurora visit: http://deved.meted.ucar.edu/hao/aurora/



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