orbitalradie

Orbitalradie is a term used in discussions of orbital mechanics to refer to the instantaneous radial distance between an orbiting body and the primary focus of its orbit. The quantity is commonly denoted r in standard mathematical treatments and is a fundamental part of describing orbital motion.

For a bound Keplerian orbit with semi-major axis a and eccentricity e, the radial distance as a function of true anomaly ν is r = a(1 - e^2) / (1 + e cos ν). When ν = 0, r = a(1 - e) (the pericenter distance). When ν = π, r = a(1 + e) (the apocenter distance). In a circular orbit (e = 0), r is constant and equals a.

Orbitalradie captures the radial component of orbital motion, varying with eccentricity and true anomaly but not by the orbital plane’s orientation. It describes how far the body is from the central focus at any point in the orbit, independent of inclination or node position, which describe orientation rather than distance.

In practice, the term orbitalradie is not widely standardized in scholarly literature; most authors simply use r or refer to pericenter and apocenter distances. It may appear in pedagogical texts or in worldbuilding contexts where a compact keyword for radial distance in orbital paths is useful. See also orbital radius, periapsis, and apoapsis.