Question

To completely describe a circular orbit, around a given point in a plane, all you need is to give the radius. How many quantities do you need to completely describe an elliptical orbit, about a point in a plane, & explain what are they are?

Answer 1

In case of a circle, all lines that pass through the center called as diameters are equal in length.

In case of an ellipse, lines that we draw through the center vary in length.

The line that passes from one end to the other and includes both foci is called the major axis, and this is the longest distance between two points on the ellipse.

The line that is perpendicular to the major axis at its center is called the minor axis, and it is the shortest distance between two points on the ellipse.

The eccentricity of elliptical orbits is the most important parameter that helps to recognise the shape of the orbit.

Apogee & Perigee distance is also required for elliptical orbits.