How hot is aurora? Has anyone done research on how hot aurora is?
I mean if it is plasma it should be hot and since it is emitting mostly green light due to nitrogen (~78%) in the air, could it then be considered that it is at least temperature at which nitrogen turns to plasma?
I have tried looking it up in Wikipedia but could not find any data of temperature.
 A: A quick google search for "aurora plasma temperature" brings up several interesting results, which seem fond of reporting temperatures in electron volts. That's entirely sensible, but probably not quite what you want. While we could do some math to convert those measurements to Kelvin, Rocket measurements of plasma densities and temperatures in visual aurora by A. G. McNamara, however, conveniently reports temperatures in Kelvin already. According to that source, the temperature of the electron plasma in an aurora ranges from 500 K to 1400 K. Note, however, that the density, and therefore the total heat capacity, of the plasma is very low; the altitude at which auroras occur is practically outer space. So, if you somehow managed to fly up there and stick your hand in one, it probably wouldn't feel all that warm.
A: I don't think it makes sense to talk about a temperature with regard to Aurora effects.  It's an epiphenomenon, independent of temperature.  
It's rather like asking "how fast is a car engine moving down the highway?" -- wholly dependent on your frame of reference.  
In this case the difficulty is using the term "temperature", which is too tied to perception to differentiate a purely physical answer. 
