Question

Which proportionality does Kepler’s third law describe?

Answer 1

size of a planet's orbit to sidereal period of the orbit

Answer 2

The third law of Kepler describes the proportionality of the orbital period and the semi-major axis of the orbit.

The square of the period of the orbit of a planet is proportional to the cube of the semi-major axis of the orbit.

The equation of the law is as follows:

`(T^2)/(a^3)=constant`

Where
`T` is the period and
`a` is the semi-major axis.