Extragalactic stars in my eyes

For centuries, astronomers scratched their heads and wondered what the hell these weird “spiral nebulae” in the sky were.

They showed up pretty much everywhere they looked. Some were small, some big, some were amorphous blobs, some showed clear spiral or other structure. Astronomers knew that some nebulae — Latin for “fog” — were gaseous by the end of the 19th century, but the true nature of their diversity remained elusive. Some astronomers speculated that some of these were separate galaxies ...