moment of inertia about axis = 0.4*\({r}^2_{e}\) = 0.4*6371^2 = 1.63*10^7 m2
moment of inertia about sun = 0.4*\({r}^2_{e}\) + \({O}^2_{e}\) = 1.63*10^7 + 149598261^2 =2.237*10^16 m2
Proportion of angular momentum with spin \(\cfrac{0.4*{r}^{2}_{e}}{2*0.4*{r}_{e}^{2} + {O}^{2}_{e}}\) = 0.00000000072
Proportion of angular momentum with rotation \(\cfrac{0.4*{r}^{2}_{e} + {O}^{2}_{e}}{2*0.4*{r}^{2}_{e} + {O}^{2}_{e}}\) = 0.9999999992
Since moment of inertia for rotation is large compared to the moment of inertia for spin, almost none of the initial angular momentum is allocated to spin, but yet,
angular momentum of spin = 0.4*\({r}_{e}\)v =0.4*6371*0.4651 = 1.1850*10^3 km2s-1
actual angular momentum \(\cfrac {spin}{rotation}\) = 0.00000026
where Earth spin speed, v = 0.4651 kms-1,\({r}_{e}\) = Earth radius = 6371 km and \({O}_{e}\) is orbital distance and V is Earth's Rotational speed.
Earth must have acquired more spins through collisions after being captured by the Sun. (Every thing is in per unit mass, so the unit may not add up.)