Gaia: Understanding the Galaxy

The GAIA Observatory, ESA's Cornerstone 6 mission, addresses the origin and evolution of our Galaxy, and a host of other scientific challenges. GAIA will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy and throughout the Local Group, about one per cent of the Galactic stellar population. Combined with astrophysical information for each star, provided by on-board multi-colour photometry, these data will have the precision and depth necessary to address the three key questions which underlie the GAIA science case: When did the stars in the Milky Way form? When and how was the Milky Way assembled? What is the distribution of dark matter in our Galaxy? The accurate stellar data acquired for this purpose will also have an enormous impact on all areas of stellar astrophysics, including luminosity calibrations, structural studies, and the cosmic distance scale. Additional scientific products include detection and orbital classification of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our Solar System, including near-Earth objects, through galaxies in the nearby Universe, to some 500 000 distant quasars. GAIA will also provide a number of stringent new tests of general relativity and cosmology. There are many scientific tasks to optimise GAIA which demand immediate effort, providing an ideal opportunity to play a major role in the project, and in the future of astronomy. Those interested in being part of GAIA activities, or wanting to know more, should contact Michael Perryman You can make your own three-dimensional model of the GAIA satellite by downloading the instructions and model parts from the WWW page. To make the model all you need is paper, glue, scissors and a spent match stick.