Is Gravity Lower at the Earth’s Equator and What Does This Have to Do With the Moon’s Orbit?

The magnitude gravitational field due to a point mass looks like this: If you are outside an object with spherical symmetry then the direction of this gravitational field points towards the center of the Earth and decreases in magnitude as you get farther away. It’s possible to make a visual representation of this with python (<a href="https://trinket.io/glowscript/ed59057b2b" rel="noopener ugc nofollow" target="_blank">full code here</a>). <img alt="" src="https://miro.medium.com/v2/resize:fit:518/1*M79vm_HvDtGROsktlLlQgQ.png" style="height:298px; width:518px" /> However, the Earth is not actually a perfect sphere and it doesn’t have perfectly spherical symmetry. Different parts of the Earth have different densities (because of variations in rocks and stuff). It’s possible to map these gravitational variations using satellites. <a href="https://rjallain.medium.com/is-gravity-lower-at-the-earths-equator-and-what-does-this-have-to-do-with-the-moon-s-orbit-e0a6c2b37073">Website</a>