The Phemu03 campaign of observation of the mutual phenomena of the Galilean satellites of Jupiter provides the opportunity to show how a very simple astronomical observation may be reached in information and is, in fact, the link between theoretical works and the exploration and knowledge of the solar system.

We study here the problems related to the Galilean satellites. As seen with a small telescope, the galilean satellites look like a small solar system where all the dynamical problems are present: mutual perturbations between the satellites, presence of Jupiter, the Sun and the planet Saturn. One will find a description of the Galilean satellites in pages dedicated to these objects. The Galilean satellites are not only a very complex problem for the dynamical modelization of their motions: they are also very amazing worlds: active volcanism on Io, ice-pack on Europa, ice and rocks crust on Ganymede and Callisto. Some web sites propose pages on the Galilean satellites (The "nine planets" of Bill Arnett or Views of the Solar System" by C.J. Hamilton or Promenade dans le système solaire). Modeling the tidal effects is very important: the interiors of the satellites may be described through the precise observation of these tidal effects reachable with a high precision astrometry. The observation of the mutual events will allow to reach this goal.

The mutual events are observable only every six years for nine months but observations of eclipses or astrometric direct observations may be performed any time and are also interesting. The observation of the eclipses by Jupiter has been performed since Galileo by generations of astronomers.

The efficiency of the observation of the mutual events comes from the network organization of the observers. Observations must be coordinated in order to catch as many events as possible. Amateur astronomers joined the network since these events are observable through a small telescope. Students in high schools using a small telescope will be able to watch the show of the mutual occultations and eclipses and also able to record some of these events. They may contact other groups willing to observe and exchange their experiences in observation. A page for the contacts between the groups interested in this educational project is available. Please, feel free to contact us at phemu@imcce.fr

During the colloquium Hands-on-Universe HOU held in Paris (France) in July 2002, a communication has been made in order to present this project.

The Phemu03 page provides a number of links useful for the understanding of these events, especially the Technical notes which are a good introduction to the explanation of the mutual phenomena.

For those willing to participate to the campaign, a page is dedicated to the observations and to their analysis.