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.
The celestial critter in the new Hubble telescope photo is actually a cloud of gas stretching one light-year (10 trillion kilometers) across, scientists said. This cloud is in the process of collapsing under its own gravity to give birth to a star — but it's a race against time, because the established bright stars in its vicinity are fighting this process.
Early on the morning of Dec. 19, 2013, the pre-dawn sky above the coastal town of Kourou in French Guiana was briefly sliced by the brilliant exhaust of a Soyuz VS06 rocket as it ferried ESA's "billion-star surveyor" Gaia into space, on its way to begin a five-year mission to map the precise locations of our galaxy's stars. From its position in orbit around L2 Gaia will ultimately catalog the positions of over a billion stars… and in the meantime it will also locate a surprising amount of Jupiter-sized exoplanets – an estimated 21,000 by the end of its primary mission in 2019.