  The Gaia space project, planned for launch in 2011, is one of the ESA
cornerstone missions, and will provide astrometric, photometric and
spectroscopic data of very high quality for about one billion stars brighter
than V=20. This will allow to reach an unprecedented level of information and
knowledge on several of the most fundamental astrophysical issues, such as
mapping of the Milky Way, stellar physics (classification and
parameterization), Galactic kinematics and dynamics, study of the resolved
stellar populations in the Local Group, distance scale and age of the Universe,
dark matter distribution (potential tracers), reference frame (quasars,
astrometry), planet detection, fundamental physics, Solar physics, Solar system
science. I will present a description of the instrument and its main
characteristics, and discuss a few specific science cases where Gaia data
promise to contribute fundamental improvement within the scope of this
Symposium.
