Explanation:
We have, a pendulum on a planet, oscillates with a time period 5 sec. The formula used to find the time period is given by :

l is length of the pendulum
g is acceleration due to gravity on which it is placed
It is clear that, the time period of pendulum is independent of the mass. Hence, if the mass is increased six times, its time period remains the same.
Conduction and convection both require some material substance
to move heat from one place to another, and there's none of that
between the sun and Earth.
The only way for thermal energy to move from place to place with
nothing in between is by the process of radiation, and that's how
it gets here from the sun.