Comets are not balls of fire dispatched from the sun. Nor is the sun actually 'fire' as we commonly think of it. The sun doesn't generate energy from chemical interactions, but from nuclear interactions. ALL of the evidence that we have points to this as a basic fact. If a piece of the sun was shot out and away, the gravity wouldn't be sufficient to hold it together as a mini-sun.
Spectroscopy firmly established that comets were "dirty iceballs." They appear bright because their albedo is so high. Albedo is the percentage of incident light that is reflected. Why are venus and jupiter so bright when they are even farther away when we can see them? Not because they are "fiery," but because they reflect incident light!
Finally, we have slammed a "bullet" into a comet and gotten REALLY close-up pictures, making it even better established. We even have quite good (composite) pictures. Check out
http://www.nytimes.com/2005/09/07/science/07comet.htmlScience isn't about taking a Holy Reference Manual and trying to confabulate ways of justifying its contents. That's pretend science. Real science is about trying to find out how things ACTUALLY work - and it starts with a careful examination of the available evidence.
This thread belongs over in "Not Quite Science."