It pulls from research and knowledge about human perception, acoustics, design, the arts, engineering, computer programming, and in this case, astronomy.
The investigation of astronomy soon led to advances in physics. For example, German astronomer Johannes Kepler attempted an explanation of planetary orbits around the sun.
Since Aunt Nellie could have provided him with financial support if he ran out of money, it is likely that Orwell's decision was primarily motivated by literary research.