  Context. Bright stellar positions are now known with an uncertainty below 1
mas thanks to Gaia DR2. Between 2019-2020, the Galactic plane will be the
background of Jupiter. The dense stellar background will lead to an increase in
the number of occultations, while the Gaia DR2 catalogue will reduce the
prediction uncertainties for the shadow path.
  Aims. We observed a stellar occultation by the Galilean moon Europa (J2) and
propose a campaign for observing stellar occultations for all Galilean moons.
  Methods. During a predicted period of time, we measured the light flux of the
occulted star and the object to determine the time when the flux dropped with
respect to one or more reference stars, and the time that it rose again for
each observational station. The chords obtained from these observations allowed
us to determine apparent sizes, oblatness, and positions with kilometre
accuracy.
  Results. We present results obtained from the first stellar occultation by
the Galilean moon Europa observed on 2017 March 31. The apparent fitted ellipse
presents an equivalent radius of 1561.2 $\pm$ 3.6 km and oblatenesses 0.0010
$\pm$ 0.0028. A very precise Europa position was determined with an uncertainty
of 0.8 mas. We also present prospects for a campaign to observe the future
events that will occur between 2019 and 2021 for all Galilean moons.
  Conclusions. Stellar occultation is a suitable technique for obtaining
physical parameters and highly accurate positions of bright satellites close to
their primary. A number of successful events can render the 3D shapes of the
Galilean moons with high accuracy. We encourage the observational community
(amateurs included) to observe the future predicted events.
