I really wish I'd see someone finally prove once and for all the Earth is round by using holonomy, a side effect of curved spaces that increases an object rotation when its only moving in translations. This is possible on a sphere but impossible on a flat surface, and a purely mathematical concept (so no reliance on photoshopped pictures, or various kind of light pollution in the atmosphere, or weird optical illusion like on water). Determining whether or not holonomy is a thing on Earth will 100% prove if its a curved space or not.