[Ethan Clive Osgoode]

The point of a two body model is to simplify everything as much as possible, and reduce the number of variables.

Well then, let's take the simplest solution. Merely observe how the Sun moves against the stars and that's the end of it.

[LeGrande]

Well then, let's take the simplest solution. Merely observe how the Sun moves against the stars and that's the end of it.

What does that tell you?