He said the sun was a hot rock, not a god, and was charged with a crime for it

Anaxagoras proposed that a cosmic force called Nous ('Mind') set the universe spinning and separating into its parts, and argued the sun wasn't a deity but simply an incandescent stone larger than the Peloponnese. After decades in Athens, he was prosecuted for impiety over the claim and forced to flee the city.

— Anaxagoras, Fragments of Anaxagoras — 5th century BCE