A number of years ago I took a college level astronomy course. I enjoyed it immensely but to this day, I am still amazed at how much in cosmology is unknown, and that which is known falls into the category of this is the model which best fits most of the data. Its that modifier which fascinated me.
Perhaps it naive but through grammar school, and high school I was left with the impression that astronomers were rapidly closing in on a fairly comprehensive accounting for all the wiggly bits and mysteries which make up the universe. Except they weren’t.