Gaia is a satellite mission of the European Space Agency, launched in 2013. It is operating today (early 2024), and it should remain operational until about late 2024–25.  Because of the enormous amount of data processing involved, improved catalogues will continue to be released well after the end of satellite operations, probably until around 2030.

Gaia's goal is to measure the distances and motions of more than two billion stars in our Galaxy and beyond, all with unprecedented accuracy, barely imaginable even 25 years ago. These observations are enabling an enormous advance in our understanding of the Universe. As of early 2024, several thousand scientific papers have been written on its findings.  The ESA Gaia www pages include many topical news highlights.

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Gaia builds on the success of ESA's pioneering Hipparcos mission, which was operated in orbit between 1989–1993.  The Hipparcos Catalogue of nearly 120,000 star positions, distances, and space motions was published in 1997.