  Hubble's law, which states a linear increase in velocities with distances,
can physically be understood in terms of an acceleration cH. This work proposes
a connection between this "universal" acceleration seen in the solar system and
the anomalous acceleration acting on the Pioneer 10/11 spacecraft, in which the
Hubble constant inferred from Pioneer 10/11 data is ~ 87 km/s/Mpc. Its physical
implication is discussed in relation with Mach's principle.
