The oblate spheroid is how r is described for earth, with naive to pretty-good mathematical assumptions regarding dynamics.

A person could integrate over this spheroid as opposed to flattening it to calculate its volume. I say that as a rebuke to those in my own country who have announced their willingness to take the whole pumpkin and flatten it, like their flat earth views on almost everything, not on those who deform space to solve problems.

And now we're being hit with pumpkin spice everything, and it's not like one can avoid it, much like the sun....