What causes electrons in the aurora to accelerate and emit radiation?

[SpitfireAce]

I'm just wondering whether anyone has any theories as to what causes the electrons in the Aurora Borealis to accelerate (emitting e.m radiation)?

 

[smallphi]

The charged particles coming from sun hit atoms in Earth's atmosphere. The atoms get in upper quantum level and then deexcite by emitting fluorescent light:

http://en.wikipedia.org/wiki/Aurora_(astronomy)

 

[SpitfireAce]

but that's the reason the sky is blue, I thought something special was going on with the aurora... something like the solar wind stretching the Earth's magnetic field, until it snaps and releases its energy, sort of like what happens when the magnetic field of the sun gets distorted and snaps resulting in coronal mass emissions... I am not actually sure where the accelerating electrons come in... but I read that this was the subject of a lot of recent research (that and the complex patterns produced)

 

[cesiumfrog]

no, that isn't the reason the sky is blue (search PF for a full explanation).

 

[FUNKER]

the sky is blue due to the fact that the blue end of the spectrum is scattered because the atmosphere is comprised of molecules that are of the order (in size) of the blue wavelength hence the blue light appears 'everywhere' overhead

 

[cesiumfrog]

See, neither charged nor excited particles

 

[Garth]

the sky is blue due to the fact that the blue end of the spectrum is scattered because the atmosphere is comprised of molecules that are of the order (in size) of the blue wavelength hence the blue light appears 'everywhere' overhead

Actually, dust particles in the atmosphere, as in Reflection Nebulae, which are also blueish in colour, also as with cigarette smoke.

The size of the particles is such that they scatter the blue frequency most efficiently.

Garth

 

[SpitfireAce]

whoops, I didn't notice that he wrote charged particles (I believe I thought it said "photons"), in any case... the sun is constantly emitting solar wind isn't it, why do we only see the aurora during the winter? and why the complex swirls instead of just a ubiquitous green tint

 

[Garth]

whoops, I didn't notice that he wrote charged particles (I believe I thought it said "photons"), in any case... the sun is constantly emitting solar wind isn't it, why do we only see the aurora during the winter?

Because it is 'dark in winter'?

and why the complex swirls instead of just a ubiquitous green tint

The solar wind is not constant but fluctuates and its strength varies depending on the phase of the 11 year sun-spot cycle.

Garth

 

[H8wm4m]

The size of the particles is such that they scatter the blue frequency most efficiently

Wouldn't all of the dust particles have to be nearly uniform in size to be so partial to blue? What an extraordinary coincidence.
Why doesn't the remaining light from which the blue was extracted create odd color effects, and why doesn't the spectrum produced by rainbows and prisms indicate a shortage of blues?

 

[russ_watters]

Yes, it isn't dust, it's the gases: http://www.sciencemadesimple.com/sky_blue.html