Instance information
unit: m^3kg^-1s^-1 or N(m/kg)^2
The gravitational constant, denoted G, is an empirical physical constant involved in the calculation of the gravitational attraction between objects with mass. It appears in Newton's law of universal gravitation and in Einstein's theory of general relativity. It is also known as the universal gravitational constant, Newton's constant, and colloquially Big G.[1] It should not be confused with "little g" (g), which is the local gravitational field (equivalent to the free-fall acceleration[2]), especially that at the Earth's surface; see Earth's gravity and Standard gravity. According to the law of universal gravitation, the attractive force (F) between two bodies is proportional to the product of their masses (m1 and m2), and inversely proportional to the square of the distance (r) between them: F = G \frac{m_1 m_2}{r^2}\ The constant of proportionality, G, is the gravitational constant. The gravitational constant is perhaps the most difficult physical constant to measure to high accuracy.[3] In SI units, the 2006 CODATA-recommended value of the gravitational constant is:[4] G = 6.67428 \times 10^{-11} \ \mbox{m}^3 \ \mbox{kg}^{-1} \ \mbox{s}^{-2} = 6.67428 \times 10^{-11} \ {\rm N}\, {\rm (m/kg)^2} with relative standard uncertainty 1 part in 104. source: http://en.wikipedia.org/wiki/Gravitational_constant