Randallw: "... don't constellations change as time goes by."
Depends on the constellation and the time period. As seen from Earth, in 50,000 years Cassiopeia will change significantly, Orion hardly at all.
http://www.astro.ubc.ca/~scharein/applets/#ProperMotion
As I recall from the series, the Twelve Tribes supposedly left Kobol about 2,000 (Earth?) years ago. Assuming the Thirteenth Tribe left at the same time, it would have to reach Earth and send back a sky map before Kobol fell into ruins, i.e. no more than 2,000 years ago. So the constellations should still be recognizable from the vicinity of Sol. If the Thirteenth Tribe left
before the others, then all bets are off.
On the other hand, real-world paleontological evidence and the Colonial racial mix make it pretty clear that humanity originated on Earth. That means that humans voyaged from Earth to Kobol (bringing their sky map) some unknown time
before the migration of the Twelve Tribes, and we have no way of knowing if Earth's constellations are still recognizable. BTW, Earth-to-Kobol migration is consistent with the Colonials' discoveries on Kobol: apparently there are no sky maps from any of the Twelve Colonies, meaning that Kobol's inhabitants considered Earth more important for some reason.