At first glance it seems odd that astronomy makes the seven Liberal Arts. Science makes sense, by why just astronomy? Why not chemistry or physics?
The short answer is that astronomy was the only mature science in the pre-modern world. The study of physics was limited to mechanics and knowledge necessary for engineering—it was not a speculative science in its own right. In similar fashion, the study of chemistry was completely non-scientific in the ancient and medieval worlds. To the extent that our ancestors had anything resembling chemistry it was what we would call to alchemy and it was often infused with magic. While the experiments of alchemists did yield results that were used by later scientists, their pursuits and study were by no means scientific.
Still, what about other sciences? What about biology, botany, zoology, and human anatomy? Plants and animals were indeed studied, but these pursuits were not considered scientific. The study of plants and animals requires the close observation of the physical world and for this reason it was lumped in with philosophy—those that studied the natural world were called natural philosophers. Philosophy as a separate, speculative pursuit detached from the physical world is a modern development. Human anatomy was not studied in scientific fashion until the modern era because both Christians and pagans alike had an aversion to dissecting dead human beings. It was only within the past few centuries that people overcame this taboo and we grew in our knowledge of the body.
Astronomy, then, was the only mature science in the ancient and medieval eras. This is not to say that our ideas of the cosmos have not changed, they have, though not as greatly as most people think. Why did astronomy develop first? Knowledge of the stars was essential for transportation, but also for accurate calendars. Accurate calendars were essential for knowing the right day to plant and harvest as well as the correct dates for religious festivals (and religious timing was very important for pagans). The development of astronomy was simply a matter of survival.
Outside of an introduction in grammar school, we at Charis don’t teach astronomy as an independent subject. Students do study some astronomy, but as a subset of physics. Our goal in teaching astronomy, physics, and science in general is that students would learn about God’s order and design in the universe. Science should be about understanding the world, but it should not end there. Someone that only sees patterns and structures and order and design sees things incompletely. God made all and so everything, in some way and to some degree, reflects God’s glory. Science is a great way to understand what God has made and, in so doing, recognize His power, wisdom, and glory.