What is the semi-minor axis of a planet?
An ellipse can be defined by its two axes – a length across the ellipse from one end to the other – the long way – and another line across the ellipse from one side to the other – the short way. These are both lines defined symmetrically relative to the shape of the ellipse – they don’t go from one corner to the other, they terminate at the farthest reaches of the ellipse in each symmetric axis. The minor axis is the “short way” length, and the semiminor axis is 1/2 of that length, as shown in the link below: http://www.mathopenref.com/ellipsesemiax… ADDED: The aphelion is actually the farthest, not the closest distance from the sun to the ellipse. The semimajor (not semiminor) axis can be obtained by adding the aphelion to the perihelion and dividing the result by two. ADDED: There seems to be a lot of confusion here. Perihelion is the distance from the focus of an ellipse to the ellipse itself at closest app
