I'm looking for the title of a SF novel that follows an alien civilization through technological eras as it tries to find a way to prevent the destruction of its sun. I believe the novel was published in the 1970s or 1980s. It was written in English and released as a mass market paperback.
The novel opens in the medieval technology era. The first protagonist is an astronomer whose observations of the sky cause him to realize their home solar system is in cosmological peril. (Sorry, I can't remember the specific cause of the impending doom.) The astronomer must now convince everyone of the gravity of the situation, a task made difficult by the religious institutions and political conflicts of the world.
Once the alien civilization realizes the seriousness of the problem, the novel shifts to a race against time, through technological eras, as its scientists work to find a way to save themselves from destruction.
A unique aspect of the alien civilization is that it is very biology-focused. Where humanity would have fabricated something out of metal, this civilization's technology harnesses biological engineering (selective breeding, genetic engineering, etc) to accomplish the same task.
I hope this is enough information to jog someone's memory!