  The astronomer E.V. Pitjeva, by analyzing with the EPM2008 ephemerides a
large number of planetary observations including also two years (2004-2006) of
normal points from the Cassini spacecraft, phenomenologically estimated a
statistically significant non-zero correction to the usual
Newtonian/Einsteinian secular precession of the longitude of the perihelion of
Saturn, i.e. \Delta\dot\varpi_Sat = -0.006 +/- 0.002 arcsec/cy; the formal,
statistical error is 0.0007 arcsec/cy. It can be explained neither by any of
the standard classical and general relativistic dynamical effects
mismodelled/unmodelled in the force models of the EPM2008 ephemerides nor by
several exotic modifications of gravity recently put forth to accommodate
certain cosmological/astrophysical observations without resorting to dark
energy/dark matter. Both independent analyses by other teams of astronomers and
further processing of larger data sets from Cassini will be helpful in
clarifying the nature and the true existence of the anomalous precession of the
perihelion of Saturn.
