semi-major
Longer ellipse radius
Semi-major describes half of the longest axis of an ellipse, measured from the center to the edge.
The term appears almost exclusively in astronomy and orbital mechanics, where the semi-major axis determines the size of a planet's or satellite's orbit: The semi-major axis of Earth's orbit is about 150 million kilometers.
The corresponding short dimension is the semi-minor axis.
Rotation reference line
- ellipseConic section curve
- conicTapering to apex
- hyperbolaCurve with two branches
- parabolaSymmetrical open plane curve
focus · diameter · radius · minor · length · perpendicular · directrix · vertex
Unconventional behavior or nature
- fociCentral points of convergence
- aphelionFarthest point from sun
- perihelionOrbital point nearest sun
- ellipticalOval-shaped or indirect
inclination · apogee · perigee · gravitation · apsis · node · precession · barycenter
axis
Rotation reference line
parabola · focus · diameter · radius · minor · length · perpendicular · directrix · vertex · center
eccentricity
Unconventional behavior or nature
- fociCentral points of convergence
- aphelionFarthest point from sun
- perihelionOrbital point nearest sun
elliptical · inclination · apogee · perigee · gravitation · apsis · node · precession · barycenter · ephemeris