Gravitation induced shrinkage of Mercury's orbit

In general relativity, the Mercury's orbit becomes approximately elliptical and the its perihelion has thus an additional advance. We demonstrate, meanwhile, that in comparison of those given by the Newton's theory of gravitation for the orbit of the Mercury, the circumference and the area are reduced by $40.39$ km and $2.35\ast10^{9}$ km$^{2}$, respectively, beside the major-axis contraction pointed out recently, and all are produced by the curved space within the Einstein's theory of gravitation. Since the resolution power of present astronomical distance measurement technology reaches $one$ kilometer, the shrinkage of Mercury's orbit can then be observable.