Planetology: natural planetary satellites

The interest of enlarging the time interval of the observation sets is to allow the quantification of tidal effects in their motion. Tidal effects from Jupiter on the satellites make an accelration in the motion of the satellites. This effect is cumulative and large observational interval (one century) is required to put into evidence this effect. The old photographic plates are of high interest for that purpose.

A Galilean satellites plate: around the center of the plate which shows several exposures of the Jovian system, we may detect reference stars of the Gaia catalogue.

The planet Mars observed through a metallic filter allowing to detect the faint satellites close to the planet.

A plate with three exposures of the Martian system: the filter has not the same shape than on the previous plate.

The field of the Saturnian system with several satellites.

This figure shows the influence of the tidal effects on the motion of the satellites.