Chapter 57 The third section Xuan Ye said

In Gaitian theory and Huntian theory, the sky is a shell structure, and the sun, moon and stars are all attached to the sky shell. Xuan Ye said that there is no solid sky shell above the ground, and the reason why the sky appears blue is because it is too far away from us.Gas is everywhere outside the earth. The sun, moon, planets, stars, and even the Milky Way are all luminous gases. Driven by the gas, they come and go freely without interfering with each other. Although Xuan Ye said that it has a close to real understanding of the material structure of the universe, it has not developed a supporting calculation model, but has focused more on speculative speculation, which eventually led to it being developed into a kind of metaphysics.Therefore, Xuan Ye theory cannot be called a complete theory of the universe.