But modern science claim that the earth does NOT have a uniform depth, but rather has a lager radius at the equator than it does at the poles.
(It seems? How do they know it is 3963 miles to the center if they've only been able to dig 8 miles down?)
From nasa.gov:
There goes "perfection".
They say that it's an "oblate spheroid" due to
lateral forces from the so-called force(s) of gravity around the Earth and its surface, etc. This how they try to say that it has squeezed-in polar caps and an equatorial bulge, but it is false. There aren't lateral forces from "gravity" around the surface of the Earth and the Earth is not moving to orbit the Sun. It is a perfect sphere.
Elcano completed Magellan's circuмnavigation of the globe back in 1522, 22 years before Copernicus published his erroneous book. Drake circuмnavigated it later. Others have circuмnavigated it too, so gradually they were able to figure its dimensions with greater accuracy, also as a sphere, having circuмference and radius. to be very general, as there are six cosmic directions in space, if you say six times radius you get circuмference. If you divide circuмference by six you get radius.
Before that they were able to figure the Moon is something about 60 Earth radii away, so there goes the number 6 once more which is essential in the universal relation of space.