Hi,
My father is an avid amateur astronomer who lives in Maryland and has really grown to love the hobby during his retirement.
He has since writen an article or two (one of them recently published in Astronomy magazine) regarding his favorite portion of astronomy which is exo-planets.
Whenever I have the chance to visit him, he enjoys showing me Saturn, the Moon, Mars, etc.. through his large backyard tracking telescope. The clarity of being able to see features, such as Saturns rings, is pretty amazing.
One of the coolest things we tracked that I saw from his telescope was the International Space Station orbiting Earth. His telescope was high powered enough that we could see the solar panels and center tube.
If Flat Earthers believe space travel is a hoax from NASA, but that we saw a clear ISS orbiting overhead from space, than space travel and man made item(s) orbiting the Earth are not a hoax.
I was wondering if any Flat Earthers have also seen the ISS orbiting via high-powered telescope. It's pretty cool and amazing to see this for yourselves.