EntityQ3568· pop 30· linked from 118 articlesfocusSign in to savefixed reference point; special points with reference to which any of a variety of curves is constructedConnectionssemi-axisEntityEarthConceptSunConceptMoonConceptSolar SystemEntityPlutoEntitygeometryEntitygravityEntitycircleEntitynatural satelliteEntitylineEntityradiusEntityellipseEntityCharonEntitypolynomialEntityparabolaEntityconic sectionEntityabsolute valueEntitybinary starEntitycurveEntityCategoriesConic sectionsGeometric centers