On the concept of periapsis in Hill's problem
The authors consider the Hill's problem, i.e. investigate the relative motion of two small masses gravitationally interacting with each other and perturbed by a large distant body (as it first was formulated by Hill for Moon, Earth and Sun). A concept of the closest approach is analyzed resulting in a partitioning of the position space (the libration point region, the region of asymptotic variations of quasi-circular orbits, the low energy escape region, the capture region etc.).
scientific article; zbMATH DE number 2139794