What causes a Aurora Borealis?

Question

What causes a Aurora Borealis?

Answer 1

I am a professional aurora photographer.  Three things cause the auroras.

There is always some aurora happening all the time on both the north and south poles.  Some days and nights it cannot be seen - this is the solar wind at work.

Next are solar flares - CME"s - coronal mass ejections - these are unpredictable with the exception of maybe a few hours of warning.  By far, strong solar flares create some of the most beautiful and spectacular auroras.

Last are the sunspots.  When of these is pointed directly at the earth they emit particals that cause the aurora.

I some wonderful technical links on my web site, and you can see some of my aurora photography at www.northpolegallery.com

Answer 2

Aurora Borealis  is caused by charged solar-wind particles reacting with the atmosphere of the earth.

What actually happens is that the charged solar-wind particles are deflected  towards the poles by the earth's magnetic field while entering the upper atmosphere.As the particles spiral down the magnetic lines of force,they bombard the gas molecules,causing them to emit coloured light.

Answer 3

High energy particles from the sun hit the earths magnetic field resulting in a plasma light show

Answer 4

When the charged particles of the solar wind approach the earth, they move along the lines of force of the earth's magnetic field, which tends to bring most of them into the ionosphere at high northern and southern magnetic latitudes. There they excite the air molecules. The air is thin enough so that the recombination can take a little while. When the molecules de-excite, they emit light. Since nitrogen is the most common gas, the color is predominantly that typical of the nitrogen spectrum.