One year at a planet is 8 times as large as compared to the one...

According to Kepler's third law of planetary motion, the square of the time period of revolution is directly proportional to the cube of the semimajor axis of the orbit.

$T^2 \propto a^3$

\left(\dfrac{T_p}{T_e}\right)^2 = \left(\dfrac{a_p}{a_e}\right)^3$<br><br>Given that$T_p = 8 T_e$, substituting this value:<br><br>$(8)^2 = \left(\dfrac{a_p}{a_e}\right)^3$<br><br>$64 = \left(\dfrac{a_p}{a_e}\right)^3$<br><br>$\dfrac{a_p}{a_e} = (64)^{1/3} = 4$<br><br>$a_p = 4 a_e

The semimajor axis of the planet's orbit is four times as compared to that of the Earth.

Answer: The semimajor axis of the planet's orbit is four times as compared to that of the Earth.