The shape of Earth approximates an oblate spheroid, a sphere flattened along the axis from pole to pole such that there is a bulge around the equator.[95] This bulge results from the rotation of Earth, and causes the diameter at the equator to be 43 kilometres (27 mi) larger than the pole-to-pole diameter.[96] Thus the point on the surface farthest from Earth's center of mass is the summit of the equatorial Chimborazo volcano in Ecuador.[94][97][98][99] The average diameter of the reference spheroid is about 12,742 kilometres (7,918 mi), which is approximately 40,000 km/π, because the meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole through Paris, France.[100]