So I have a point to make. If galaxies and solar systems are flat, then why couldn't earth be flat? Physics has already proven that it is galaxies and solar systems are flat. From here on, I will use the prove of galaxies and solar systems being flat to argue that the earth is also flat. Circular motion is dependent on 2 factors: tangential velocity and the centripetal force or the gravitational force in this case. As the particles approach the poles, rotation around the poles are not stable, as the gravitational force is not the centripetal force to make the particles go in circles. In that case, the particles will either collapse to the center of the earth of be flung away. So the earth cant be round.