1. The problem statement, all variables and given/known data Imagine viewing an eclipse of Charon by Pluto. Assume the satellite orbit is nearly circular, of known radius a, and is viewed edge-on. Explain how you could use the observations to infer a diameter for Pluto 2. Relevant equations Orbital radius R=a 3. The attempt at a solution Pluto is totally covering Charon right? Does it sound like I should be able to look up the radius of Charon? Or just use a? I'm really stuck with this one. Thanks for your help!