Don't let anyone try to convince you that the earth is a sphere! It's actually closer to an ellipsoid. How does your airline pilot know which direction to head when he’s over the ocean with no landmarks? How do we know the exact boundaries between parcels of land and between states and countries? These are questions we answer with geodesy (sometimes known as Geodetics Engineering): the science of how we characterize the shape and size of the earth. Geodesy: https://en.wikipedia.org/wiki/Geodesy Reference Ellipsoid: https://en.wikipedia.org/wiki/Reference_ellipsoid Watch this video and the entire Practical Engineering catalog ad-free on Nebula: https://go.nebula.tv/practical-engineering Patreon: http://patreon.com/PracticalEngineering Website: http://practical.engineering/ Music: Elexive - Valley Santa (https://www.youtube.com/watch?v=TA7Hro7OYpc)