In any case, how would electrical spark phenomena appear in the vacuum of space without any surround atmosphere?
Answer Hello Carl Long, Sparks are electrons flowing from one charged body to another oppositely charged (or neutral) body. On their way from one body to the other the electrons hit atoms of the medium and excites them (ionizes them). This excitation only lasts for a short time and when the atoms relax, they give off their excitation energy as a photon. This is what we see of a spark. Without any medium (in perfect vacuum) there would be no channel of ionized atoms conducting the spark and thus the “spark” would be invisible. But it would not be a real spark, since the electrons need the conducting channel of ionized atoms to cross the isolator (air). In a perfect vacuum, after the first few electrons crossed over to the other body, the electric field is weaker and the energy is not sufficient for the electrons to cross the isolator (vacuum) any longer. So only a few electrons would “make it” and they would not make up a spark. For an in-depth treatment on lightning see: http://en.wiki
