Gaia will be the most accurate optical astronomy satellite ever built so far. Due for launch in 2011, it will continuously scan the sky for at least five years from a point in space known as the second Lagrangian point (or L2), located at about 1.6 million kilometres away from the Earth, in the direction opposite to the Sun.
Gaia’s goal is to perform the largest census of our Galaxy and build a highly accurate 3D map. The satellite will determine the position, colour and true motion of one thousand million stars. Gaia will also identify as many as 10 000 planets around other stars, and discover several tens of thousands of new bodies - comets and asteroids - in our own Solar System.