This is an amazing mission that will conduct the largest, most precise three-dimensional map of our Galaxy a census of a thousand million stars in our Galaxy. It will monitor each of its target stars about 70 times during a five-year period, precisely charting their positions, distances, movements, and changes in brightness. Gaia is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and brown dwarfs and quasars. Within our own Solar System, Gaia should also observe hundreds of thousands of asteroids. The spacecraft will also develop new tests for Einstein's General Theory of Relativity.