--these observations could only be true on a spherical earth;
--the size of the earth must be what "they" say it is.
Follow me: When I travel from Cleveland, OH to Spokane, WA, I notice that the height of the sun at any given day at what I call "sun noon" (sun directly in the south) is about six degrees lower in Spokane than in Cleveland. That's from my own personal observation. Spokane is at 47 1/2 degrees north latitude, and Cleveland is at 41 1/2. Six degrees. I've traveled the distance between the two cities by automobile many times. The maps are accurate.
The distances published coincide with the mileage on my odometer. I travel through 3 time zones of 15 degrees longitude each. 15 degrees times 24 hours equals 360 degrees, or one circumference. The lines of latitude and longitude are published accurately on maps. Each degree of latitude is 69 miles. 69 times 360 equals 24,840. Checks out. The lines of longitude grow closer together as we get farther from the equator, and they're the distance apart at any given latitude they should be if the earth were a sphere 25k miles in circumference. Checks out. Furthermore, Spokane is east in its time zone, and Cleveland west in its time zone. Therefore the sun rises and sets in Cleveland later relative to clock noon than it does in Spokane. I've checked this out, and it's accurate.
The published figures for sunrise and sunset are accurate. Go to suncalc.org if you want to see these things for yourself. Pay close attention to how long shadows are where you are and do the trig math. It checks out. This is only one example. I've been all over the world, and I pay close attention to the coordinates of every place I go to. Everything so far has checked out.
The earth has to be a sphere, and it has to be the size "they" say it is. As far a seeing lighthouses at greater distances than calculated, that could be atmospheric refraction, enabling us to see a light that is below the horizon. Just a guess. I'll have to look at that.
