Well, I think that it is, in no small part, an allusion by Bakker to the ancient idea of asology, in the sense that there was a belief that celestial events (like supernovea, comets and so on) marked "portenteous, or ominous" events in history.
So, there might well be some reason to be made that the pole star suddenly going (super)nova and increacing in brightness that actually is related to the Ark's arrival, or it could just be the the literary allusion to to the idea that it simply "must be" the case.
Also, it might possibly be an inversion of the idea of Star of Bethlehem, alluded to in the Hebrew bible, as what is called the Star Prophecy:
I shall see him, but not now: I shall behold him, but not nigh: there shall come a Star out of Jacob, and a Sceptre shall rise out of Israel, and shall smite the corners of Moab, and destroy all the children of Sheth.
— Numbers 24:17
In this case though, the star signals the arrival of the exact opposite of the savior, in the Ark. And, "coincidentally" is the place to which an "alleged savior" ascends, rather than has marking his arrival. In the end, it's likely a "trick" to get us to ascribe "meaning" based on the historical precedents of these events in our cultural history.