However, if that same rubix cube is instead 1 mile above your head, and it travels across the length of your room, you will NOT be able to see is green colored side. The rubix cube will have hardly turned at all when it gets to a position 30 feet away. You will still be looking at its white underside.
I'm sure we all agree with that, but the moon moves much more than a mile or two according to FET.
As a object increases its height it will turn slower. We do not know how slow, however. Infinitely slow? Does the slowness become imperceptible or perhaps stop turning altogether at some point? Could it be that an object turns so slow that it reaches the vanishing point before rotating to any significant degree? There is a lack of data because the maximums of perspective theory were never studied.
If something is a specific height, and from directly underneath two people traveled in opposite directions away and stopped after traveling a distance equal to it's height, they will have a 90 degree difference in their viewing angles of that object. At roughly what point, and why, would that change?
I agree
A person below the Moon would see the bottom. Two people far apart would get a 45 degree view and so 90 degrees difference to them . Theres absolutely no way all three of them would see the same view of the Moon. Altitude of the Moon makes no difference. The angles narrow down but its impossible physically for everyone to see the same side. Especially with a good old telescope. I was hoping for a good answer to this one.
Lets go back to the rubix cube example. The rubix cube is suspended 1 mile in the air and the people in the room, standing at every corner of the 30 foot by 30 foot room, will all see the same white underside of the rubix cube when they look upwards. No one is really disagreeing with this.
We do not know what relationship perspective will scale at, but to showcase a simple example of how it could all be possible, let us take that relationship and imagine that it is linear and multiply by 3000. The rubix cube is now 3000 miles (1 x 3000) in the air and instead of a 30 foot long room we have a 90,000 foot long room (30 x 3000). 90,000 feet is over 17 miles, which is more than the distance to the horizon's vanishing point near sea level. This means that the rubix cube could travel from overhead to the vanishing point and rotate less than it would if it were 1 mile in height and moving across 30 feet.
That is just one example for how perspective could scale. There are other possibilities which might result in a different outcome (imagining that the relationship is continuous like the Ancient Greeks did, for example), but since there is no available research on the maximums of perspective theory, we are not permitted to say how distant bodies will appear to the observer.