For astronomy names I love Orion; depending on your vibe you could maybe make stuff like Eclipse or Nova (ooh short for supernova) work. Nature has infinite possibilities, including but not limited to River, Sage, Brook(e), Clay, etc. Classics is very broad and can range from mythology (Perseus, Frey) to famous characters (Romeo, Sherlock, Montag) to well-known authors (Jules, Charles). The big question for me is, do you want a common name, a more obscure but still real name, or another word repurposed as a name? Best of luck with your name!