"even if we knew the whole truth, it would be very hard for us to believe it." - I agree 100%.
It took me over a year to really come to terms with the flat plane that we live on, water always seeking its level, stars spinning perfectly over the north pole, yet the earth supposedly wobbles too at some 20+%, etc.
The flatness is easily provable though. My favorite video is the one on dollarvigilante.tv called "200 proofs". I'm not trying to turn anyone into a crazy flat earther though, but it would be awesome if you could watch that 1 video to the end and really examine the points that he makes in that video.
As to what is really over our heads and what we see in the night sky, that for sure is nearly impossible to prove right now, and all we can do is speculate. I think that we live in a closed system actually, a living, breathing clock of sorts. Sounds crazy right now, I know, but the more I looked into it that is the conclusion that I have come to, not a single conclusion from one single video that I have watched or anything either. I am piecing all this together myself.
As for distance to the sun and moon, that is easily provable with a sextant. iirc, I think they are roughly 3000 miles up, they're the same size more or less, and are about 30 miles across. Even Buzz Aldrin said recently that "we didn't go there" (moon). What is the moon? Hell if I know, probably some kind of plasma disc or hologram. Heat tests have shown without a doubt too that the moon actually produces its own cool, septic light. The antithesis of what the sun produces. (see yin yang)
Please watch that "200 proofs" video. There are others, but that one really demonstrates (and gives you tasks that you can perform for yourself) much of it.
The laser tests across the great salt flats and atlantic ocean for example... If the earth curves at 8 inches per mile squared like NASA says, then it should be impossible to see the laser across those flat surfaces more that a few miles away, yet there it is.
With flir systems, we can see mountain ranges thousands of miles away. That should not be possible either if we lived on a ball that curves 8 inches per mile squared.
When the sun disappears each day, I can take a zoom lens and bring it right back up into view. Same with a boat that "disappears over the curve". Just grab my zoom lens again and bring it right back into view, hull and all.
I know what you're thinking man, I sound like a whack job. It took me awhile to really say to myself "no f*ckin way man!". We have been lied to about damn near everything.
RE: 20 Proofs NASA Faked the Moon Landings