My questions are; what causes comets to emit/eject stuff out that creates it's head and tail? I would assume it's the sun's solar wind reacting with the comet body causing it to eject small pieces out and away from the sun but what is a solar wind, I mean besides ionized gas? Is it something natural that all stars do or is it a reaction to an outside force? Does this process strip away material from a comet decreasing it's size over time or do the particles just relocate never to venture far from the comet? Can a large planets magnetic field cause a similar reaction to a comet that comes too close traveling at a high velocity and perhaps in a retrograde motion?

I am having trouble with the idea of comet Holmes illuminating in such a uniform (spherical) manner due to an impact. I suppose it is hard to tell from here and it does seem plausible but could it be a reaction similar to our Suns solar wind that is the cause? I know this last idea just adds more questions then it could answer but thats what makes it all fun for me.

Another odd thing is that comet Holmes appears to have a small tail but not in a direction away from our Sun's solar wind. I don't know how accurate this info is but if there is a tail it looks like it may be pointing in our direction.