*ahem*
Scientific Theory is not fact, I'm sorry. It is (hopefully and usually) an eminintely logical conclusion that fits (many? most?) observed facts and does not blatantly contradict any of them.
However, scientific theories can be, and indeed have been, proven wrong. Scientific thinking, when faced with more than one explanation that fits the facts, usually tends towards the simpler one. However, when at an unspecified point in the future new empirical evidence, new facts, are established, that contradict that simpler explanation without contradicting one of the others, then that theory must change to fit the facts.
The Earth revolving around the Sun is a fact, not a theory. It has been observed, measured, and verified 14 million ways from Sunday.
However, if I may toss a match into the kindling, AFAIK the theory that the universe is expanding (not referring to the Big Bang Theory, mind you) is still just a theory. Yes, it fits the facts of red-shifting in the observed galaxies in our proximity, but there is another theory to fit that fact just as well: the universe could have stopped expanding eons ago, due to gravitational forces slowing everything down, and has now begun to contract.

Logically, this works, since those galactic bodies closer to the "center" of the universe's distribution of mass would have a stronger gravitational effect pulling them "inwards" at a faster clip then the Milky Way is being pulled. Same with the galaxies "rimward" from our position - we're being pulled in faster than they are, hence the red-shifting.
Now, granted, all this is still firmly
theory - expansion or contraction - and could be overruled by some new shred of evidence at some point in the future. It is not fact, it is a logical conclusion that fits observed facts. Nothing more, nothing less.