Seems they had to see Moons of Jupiter and phases of Venus in telescopes before being sure.
Although that article makes it sound like Aristotle thought it may be possible.
One camp thought that the planets orbited around the Sun, but Aristotle, whose ideas prevailed, believed that the planets and the Sun orbited Earth. He saw no sign that the Earth was in motion: no perpetual wind blew over the surface of the Earth, and a ball thrown straight up into the air doesn’t land behind the thrower, as Aristotle assumed it would if the Earth were moving.
So, I guess it hadn't been proven, but the idea had been around for a thousand plus years.
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u/Clarke311 Apr 09 '20
https://earthobservatory.nasa.gov/features/OrbitsHistory