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More than 635 000 positional observations (mostly radiotechnical) of planetsand spacecraft (1961-2010), have been used for estimating possible changes ofthe gravitation constant, the solar mass, and semi-major axes of planets, aswell as the value of the astronomical unit, related to them. The analysis ofthe observations has been performed on the basis of the EPM2010 ephemerides ofIAA RAS in post-newtonian approximation. The obtained results indicate ondecrease in the heliocentric gravitation constant per year at the level $ \dot{GM_{Sun}}/GM_{Sun} = (-5.0 \pm 4.1) 10^{-14} (3\sigma).$ The positive secularchanges of semi-major axes $ \dot a_i/a_i$ have been obtained simultaneouslyfor the planets Mercury, Venus, Mars, Jupiter, Saturn, as expected if thegeliocentric gravitation constant is decreasing in century wise. The change ofthe mass of the Sun $M_{Sun}$ due to the solar radiation and the solar wind andthe matter dropping on the Sun (comets, meteors, asteroids and dust) wasestimated. Taking into account the maximal limits of the possible $M_{Sun}$change, the value $\dot G/G$ falls within the interval $ -4.2\cdot10^{-14} <\dot G/G < +7.5\cdot10^{-14}$ in year with the 95% probability. Theastronomical unit (au) is only connected with the geliocentric gravitationconstant by its definition. In the future, the connection between $GM_{Sun}$and au should be fixed at the certain time moment, as it is inconvenient highlyto have the changing value of the astronomical unit.

Estimations of changes of the Sun's mass and the gravitation constant from the modern observations of planets and spacecraft