1. The problem statement, all variables and given/known data I have been tasked with showing "how the mechanical energy of a planet determines the shape of its orbit", and I cannot for the life of me make sense of it. I've run into a formula, see below, but I'm not sure how to interpret it nor if it even applies in my case at all (as E is apparently the total mechanic energy, not just the planet's (or something): https://en.wikipedia.org/wiki/Orbital_eccentricity) 2. Relevant equations 3. The attempt at a solution None. I'm dumbfounded.