What’s the extent of Westeros’ astronomical knowledge? Have they had a Copernican Revolution yet? Are they aware of the existence of other planets?

Astronomy is one of those weird areas in which Westeros’ uneven technological development puts them ahead of schedule: the maesters observe the heavens with telescopes manufactured in Myr, they know the Seven Wanderers are in fact planets, they have a heliocentric model of the universe, they are quite good at tracking comets, and they are good at using the stars to help predict the changing of the seasons.