Xiao Ji 蕭吉 in the Sui Dynasty (581-618) wrote his Great Meaning of the Five Elements 五行大義, which is a manual on natural phenomena and classical Chinese metaphysics. It is an important text as it provides in great detail how Chinese civilization generally viewed both the physical world and cosmos in this period. The text incidentally was lost in China, but fortunately preserved in Japan. This is actually the case for a good many other Classical Chinese texts as well.
Xiao Ji relies heavily on citations from numerous classical texts and offers a balanced perspective in that he provides differing views. It is written in a technical style, lacking a literary polish. In my reading of the chapter on astronomy (chapter 16) I found two noteworthy things. The first is that Xiao Ji recognizes that the luminosity of the moon is a result of sunlight:
The moon is of yin essence. Its form itself is without light. It shines by means of sunlight illuminating it, just as a retainer is without power. His power is achieved through the influence of his lord.
Xiao Ji, like his predecessors, readily perceives a hierarchy in nature and frequently draws similes with court culture. Here the moon is accurately identified as lacking its own luminosity. Another accurate statement relates to the physical quality of astral bodies:
The five stars [i.e., the five visible planets of the solar system] – the Shuowen Jiezi 說文解字 states the stars are the essence of myriad phenomena. Some say the sun is divided into stars, hence its character [in Chinese] consists of the ideograph “birth” under the sun radical. The Shiji 史記 states stars are the dispersal of the essence of the metal element. It is stone when a star falls. This is the metal element. The Spring and Autumn Annals 春秋 states that a stony meteorite fell in the state of Song. It was a falling star. It is also said that a star is the essence of yin. The metal element is also yin.
The inference here is that since observed meteorites are of stone and the metal element, it follows that stars, specifically the five visible planets of the solar system, should also be comprised as such.
Such observations are noteworthy as it illustrates Chinese civilization in this period had a degree of accurate astronomical knowledge, much of it traceable to at least the Han Dynasty (206 BCE - 220 CE). Xiao Ji of course is mistaken about other things – for example, that the sun is 1000 li in diameter and 3000 li in circumference, but nevertheless his observations and conclusions are often based on observations and reasonable inferences rather than mere revelation. This differs from the Buddhist approach to astral science which was based on the revelation of scriptures. For details on this see my post here.