If it’s purely for self interest and not for a career, then the Swinburne degree is pretty good. They do a Grad Cert, Dip, Masters so you’ll have to have some undergrad, but it doesn’t have to be in science. It won’t lead you to a PhD though if that’s what you’re after.
They cover a wide range of topics in astronomy, and touch on a little astrophysics where required.
https://www.swinburne.edu.au/study/c...A-SASTRO/local