  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.
