[staunton]

The field is not uniform though. So in theory, if you know the orbit and firld exactly, you can calculate it.

In the present case, I guess the precision with which one knows the orbit and other stuff (like the exact gravitational fiel of the earth) doesn't work out.

[martincmartin]

True. It turns out, it also applies for the two body problem, as long as one body is much more massive than the other.

https://en.wikipedia.org/wiki/Orbital_period#Small_body_orbi...