[QUOTE=Nereid;817663]If this is so, then how can the "
Attiyah's Sun Theory" be tested, even in principle?
It can be tested by TERRELLA EXPERIMENTS (Birkeland's terrella experiments).
The so-called "Active Experiments" can also help in testing it.


===========

Concerning the relative contribution in the visible spectrum of the skylight(mainly aurora-produced) compared with the visible direct solar light, I say that its measurements or estimations will be hard and complicated. However, there are many visible spectra which are completely or nearly completely from auroras. For example, the visible emissions of the neutral nitogen molecules are from aurora origin since the Sun's composition is void of such neutral molecules.