u = GM = 1.32712440018 * 10^20 [m3/s2];
M = 1.9891 * 10^30 kg, the mass of the Sun;
This can be determined the gravitational constant:
G '= u / M = 1.32712440018e20 / 1.9891e30 =
6.672e-11
Similarly, for the Earth:
u_e = 3.986004418 * 10 ^ 14; M_e = 5.9736 * 10 ^ 24 kg;
G_e = u_e / M_e = 3.986004418e14 / 5.9736e24 =
6.6727e-11 [1/s^2] / [kg/m3]
clearly shows that these constants differ quite significantly.
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T ^ 2 = a ^ 3 / u;
dT / T = 3 / 2 da / a - 1 / 2 du / u;
Semi-major axis 'a' can be determined by other methods, so da = 0, and:
dT / T = -1 / 2 du / u = T / Tp = 1 / 25700
du = - 2u * T / Tp = - u / 12850;
Thus: G = G '(1 + 1 / 12850) =
6.6725e-11
Much better.
Implicitly changed the orbital periods of other planets (theoretical - modeled),
but not periods of moons! So it can be easily verified.