Yggdrasil (13th century)
In Norse cosmology, Yggdrasil was an enormous ash tree that connects the nine worlds of the mythological universe. Interpretations of it stem from the Poetic Edda of the 13th century. For hundreds of years after the popularity of Yggdrasil spread, some northern European cultures believed in warden trees and sacred trees as guardians and bringers of luck. This idea can be seen in the weirwoods in the Song of Ice and Fire books.
Earth at the Center (1568)
For hundreds of years, from ancient times to the Renaissance, it was widely believed and officially taught that the Earth was the center of the cosmos and all celestial bodies. This was largely based on the fact that the Sun, Moon, and stars appear to revolve around the Earth day after day, and because, from the point of view of somebody on Earth, the planet seems to be still. Thus, the universe was just whatever we could observe, floating around our world.
Heliocentrism (16th century onward)
Although the theory that the Sun was at the center of the galaxy can be traced back to the 3rd century BC, it wasn’t widely accepted until the scientific advancements of the Renaissance replaced the notion of geocentrism and began the Copernican Revolution.