We set up a rectangular ξ η coordinate frame in the orbital plane of the planet in such a way that the origin is in the Sun and the ξ axis points to the perihelion (Fig. 3.8)
We set up a rectangular ξ η coordinate frame in the orbital plane of the planet in sucha way that the origin is in the Sun and the ξ axis points to the perihelion (Fig. 3.8)