Axioms

Not any more it isn't. In 2019 it was redefined in terms of the Planck constant -- though, of course, its *actual value* comes down to the original French Revolutionary definition: but even that was the mass of a cubic centimetre of water at the melting point of ice. This, of course, depends on atmospheric pressure (since they didn't use the triple point), and thus indirectly on the mass of the Earth and a bunch of other contingent values -- but the current definition depends on no such things.