[autocorr]

My understanding is that the first conclusive proof that the Earth rotates was the astronomical observation of the aberration of starlight[1] in ~1730. The rotation of the Earth causes about 20 arcseconds of deflection from a stars known position, which is pretty large. The phenomena itself is due to relativistic beaming, and lead to one of the first measurements of the speed of light along with Roemer's earlier work using the moons of Jupiter as a clock in ~1680.

[1] https://en.m.wikipedia.org/wiki/Aberration_(astronomy)

[ridgeguy]

I think the 20 arc second deviation is caused by Earth's orbital velocity around the Sun. Did you intend that instead of rotation? The latter causes less than 1 arc second deviation.