Plasma is 99% of visible matter. You can have very long stretches of it across the sky out in the distance. Light passing through it, and the EM links of it, will be affected by it, as it will also affect the plasma.<quoted text>
Backwards. varying EM fields *are* light. Matter is what emits light. No matter, no emission of light (although there can be propagation).
You have charged areas of space via plasma clouds. Just like the one between us and the sun.