Answer
$F = 3.5\times 10^{22}~N$
Work Step by Step
We can find the gravitational force on the Earth due to the sun:
$F = \frac{G~M_s~M_E}{r^2}$
$F = \frac{(6.67\times 10^{-11}~N~m^2/kg^2)(2.0\times 10^{30}~kg)(5.98\times 10^{24}~kg)}{(1.5\times 10^{11}~m)^2}$
$F = 3.5\times 10^{22}~N$
In part (a), we found that the force on the Earth due to radiation pressure from the sun's radiation is $5.95\times 10^8~N$
We can see that the gravitational force on the Earth due to the sun is many orders of magnitude larger.
