  We study the population of Galactic planetary Nebulae (PNe) and their central
stars (CSs) through the analysis of their heliocentric distances and Galactic
distribution. Distances are obtained by means of a revised statistical scale,
based on an astrometrically-defined sample of CSs parallaxes from Gaia DR3 as
calibrators. The statistical scale is applied to infer distances of a
significant number (~850) of Galactic PNe, for which we deliver a new catalog
of PN distances. By adopting a circular velocity curve of the Galaxy, we also
derive 3D peculiar velocities from DR3 proper motions and published radial
velocities of a large sample (~300) of PN CSs. We date PN progenitors based
both on the best chemical abundances culled from the literature and on CS
kinematic properties, finding a confirmation of the first method with the
second. The slope of the radial oxygen gradient of the Galactic Disk traced by
the complete PNe sample amounts to -0.0144 +/- 0.00385 [dex/kpc]. Furthermore,
by distinguishing between PNe with old (> 7.5 Gyr) and young (< 1 Gyr)
progenitors, we estimate the gradient to be respectively -0.0121 +/- 0.00465
and -0.022 +/- 0.00758 [dex/kpc], thus disclosing a mild steepening since
Galaxy formation, with a slope change of 0.01 dex. These results are in broad
agreement with previous PN studies, but now based on DR3 Gaia analysis, and
also in agreement with what traced by most other Galactic probes.
