What is the Earths eal shape?
It’s not a sphere, it’s only sort of a spheroid. The actual shape of the Earth depends upon who you talk to. There are two surfaces that people refer to as the ‘shape’ of the Earth. The first is the topographic surface of the Earth. This one’s easy to understand. It’s where the Lithosphere meets either the Atmosphere or the Hydrosphere. The second is the Mean Sea Level (MSL) Geoid. It is necessary to preface ‘The Geoid’ (in capital letters) with MSL, as there are an infinite number of geoids. A geoid is an equipotential surface with respect to the gravitational acceleration of the Earth. That is to say, an object anywhere on the surface of the geoid will have the same potential energy. Another aspect of an equipotential surface is that the acceleration due to gravity is always perpendicular to the geoid. Or, gravity always points straight down towards the geoid. Or, an equipotential surface is ‘flat’ with respect to gravity. A picture of the MSL Geoid appears rugose, (rippled) from abo
