EntityQ1586270· pop 5· linked from 6 articlesVariation (astronomy)Sign in to saveperiodic perturbation of the lunar orbitConnectionsEquation of the centerEntityastronomyEntitycircleEntityLunar eclipseConceptTycho BraheEntitydegreeEntityPhilosophiæ Naturalis Principia MathematicaEntityorbital eccentricityEntityecliptic coordinate systemEntitysyzygyEntityperturbationEntitylunar monthEntityorbit of the MoonEntityErnest William BrownEntityKepler orbitEntityevectionEntitymean motionEntitylunar theoryEntityCategoriesCelestial mechanicsOrbital perturbationsOrbit of the Moon