State Kepler's law of periods (Kepler's third law) for planetary motion.

(N/A) Kepler's third law,also known as the law of periods,states that the square of the time period of revolution $(T)$ of a planet is directly proportional to the cube of the semi-major axis $(a)$ of the elliptical orbit traced out by the planet.
$T^{2} \propto a^{3}$
This can be written as:
$T^{2} = K a^{3}$
where $K$ is a constant for all planets orbiting the same star.
Defining $Q = \frac{T^{2}}{a^{3}}$,where $a$ is the semi-major axis in units of $10^{10} \ m$ and $T$ is the period of revolution in years $(y)$,the value of $Q$ remains approximately constant $(Q \approx 2.98 \times 10^{-34} \ y^{2} \ m^{-3})$.

Planet	$a$ $(10^{10} \ m)$	$T$ $(y)$	$Q$ $(10^{-34} \ y^{2} \ m^{-3})$
Mercury	$5.79$	$0.24$	$2.95$
Venus	$10.8$	$0.615$	$3.00$
Earth	$15.0$	$1$	$2.96$
Mars	$22.8$	$1.88$	$2.98$
Jupiter	$77.8$	$11.9$	$3.01$
Saturn	$143$	$29.5$	$2.98$
Uranus	$287$	$84$	$2.98$
Neptune	$450$	$165$	$2.99$
Pluto	$590$	$248$	$2.99$