"A nautical mile is a unit of measurement defined as exactly 1,852 metres (6,076.1 ft; 1.1508 mi). Historically, it was defined as one minute of latitude, which is one sixtieth of a degree of latitude. Today, it is a non-SI unit[1] which has a continued use in both air and marine navigation,[2] and for the definition of territorial waters.[3]" -- https://en.wikipedia.org/wiki/Nautical_mile As accurate as this is or may be, it isn't all that is included in measuring distance or the size of distant objects. I will show you why, below.
You guys keep confusing/conflating apparent size with angular size. Angular size corresponds a physical distance and apparent size is just how big an object looks. Either understand and acknowledge difference or you need to consider suicide.
Perhaps we do. But you keep confusing apparent size with actual size.
The following illistration is not to scale and the drawn angle is distorted by perspective but it's simplicity helps demonstrate the concept of angular size. It doesn't matter where a telephone pole is located within the field of view so long as it hasn't passed the vanishing point its angle will remain the same size. If the height of a pole is changed its angle will also change to mach the new height. This is how distance is measured and it's how a mile is defined by an angle of one minute.
Actually, this is only part of how distance is measured. Why? Because both perspective and vanishing-point have to do with the limits of the eye to see far-away objects, and to "visuallize" their size. Continue reading.
Angular size is something that can't be measured on a globe, the horizon on a globe while standing by the ocean is a curved line formed by a convex dome of water three miles away. Ships on a globe sail up, over and disappear behind the curve of the dome as they sail down below the water blocking the view. There is no vanishing point to measure angular size with, everything is hidden by curvature before that can happen. If you believe this then kill yourself.
Angular size absolutely can be measured on a globe. Its size measurement is calculated to extreme accuracy with calculus rather than trig, alone.
Here is your mistake that I alluded to, above. Both perspective and vanishing point have to do with the limits of the eye and/or other optical equipment. How's that? Essentially, there is no vanishing point when considering perspective with real and actual distance and size of distant objects.
If we had an infinitely capable viewing device, perspective would never end, except if there is an end to the universe. The angle at the distant apex of the view, might be infinitely small, but it would be continuous, except if the universe literally DOES have a limit.
The confusion exists in not precisely defining what is meant by "perspective" and "vanishing point" between forum people. Your confusion exists because you jump between definitions in your use of them, automatically, and possibly many times in a sentence and a thought. And, it exists because you are trying to apply more than one definition at the same time.
Two of the definitions you are using, even if only assumed, are:
A. Localized observations (simple sextant);
B. Universal application of localized observations.
Science has shown that things don't work like
that. They have shown it with telescopes, annual measurements (sometimes with a sextant), laser/telescope visual observations, satellite observations, calculus in the measurements, and other methods. All these combined show us that the earth definitely isn't flat.
The angle measured between two sides of the Sun and the horizon vanishing point reveals the diameter of the Sun in miles. The sextant measures angles on plane and the Sun is measured at 32'; the application and direct measument is irrifutible proof beyond a reasonable doubt the Earth is flat.
Except that the simple vanishing point location, is limited to the width of a distant object, where there is only enough light from that object, to stimulate one eye nerve "pixel."
That is what perspective really is.
Using a small telescope connected to a sextant, or even a transit, or (of course) a big telescope, or a dish array, extends the vanishing point perspective way beyond what the eye can see alone, and shows us that distant heavenly objects are far more distant than perceived by the "bare" eye, alone.
Even with atmospheric aberration, a good telescope can see a ship settling over the horizon.
If all this were not enough, consider the word "flat." What is meant by "flat?" When you get down to the microcosm, "flat" becomes meaningless in the fact that material is really made out of complexly interacting waves of electromagnetic energy.
If you judge "flat" according to the macrocosm, "flat" is simply an imprecise observation. There are mountains and valleys that cannot be seen as such, or barely observed as such, from hot air balloon distances above the earth, and certainly from high flying airplane distances. They look flat, but we know from climbing on them that they are absolutely NOT flat.
So, what really is "flat?" Isn't "flat" really an abstract term designed to describe the limits that people have when observing things? Doesn't "flat" exist to help simple people in their simple daily lives? Because when considering the small or large, "flat" doesn't really exist anywhere. So there absolutely can't be a flat earth.
