Question

Why is the value of the gravitational constant?

Answer 1

The value for the gravitational constant 'G' does not change from one attracting body to another. It is a universal constant.
Gravitational constant = $6.67408\left(31\right)\times {10}^{-11}{m}^{3}k{g}^{-1}{s}^{-2}$ (uncertainty in parenthesis) or $6.674\times {10}^{-8}c{m}^3{g}^{-1}{s}^{-2}$.