Here is the exercise: If you take all the information of NASA and the government out of the equation, how would you KNOW the earth is a sphere by using the scientific method?

By using a shop bought telescope to observe the heavenly bodies, like the way the moons of Jupiter and Saturn orbit them and not us.

By observing the shadow of the moon on the sun during an eclipse, from multiple points on earth. Then using good old fashioned geometry working out that the shadows I observe are not consistent with viewing them from a flat disc.

By travelling to an "edge country" and observing buildings in the street, which would have to be built at steeper and steeper angles the closer they got to the "edge" of the planet.

By going to a country that is purported to be on the edge of the world and walking towards said edge. If I didn't feel gravity tugging me back towards the centre of the Earth, I would know that that was consistent with living on a globe.

By watching the video of that dude that parachuted from space, and observing his view of a curved globe.

By going to the HDEV ISS live (technically not NASA) and looking at the live video link (https://eol.jsc.nasa.gov/HDEV/)

I could go on; but I won't :-)

Sorry one more! In order for gravity to work the way it does on Earth, he sun would have to be 32,000 miles away and a lot smaller than it actually is. This would be fairly easy for an amateur astronomer to verify.

OK, that really is it now :-D
Cg