How do astronomers believe the world was created?
Uh, no negatory on the "creation" aspect.
Astronomers would not support any kind of interpretation that the world was "created" as this always implies a "creator". All of the evidence we have to date suggests that the world, sun, galaxy and the entire universe "emerged" by purely physical forces and there is no need to evoke a creator or created world.
The Big Bang is the best explanation we have for the development of the universe/galaxies and the Nebular Hypothesis is the leading idea on how the solar system and our Earth formed. Suggest you do a Socratic search for similar questions that can provide you with details.