For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
You should try Space Engine. It’s a program to explore the universe, based on real telescope data. It also has the ability to procedurally generate galaxies, planets, and stars in unobserved parts of the universe.