Gaia: Ten years observing our cosmic neighbourhood

On 27 March 2025, the Gaia satellite was inserted into its retirement orbit and finally shut down, "passivated", after more than 10 years of outstanding service to the astronomical community. Launched by the European Space Agency (ESA) in December 2013, Gaia has been scanning the sky to create a multi-dimensional map of nearly 2 billion (2E9) stars and other objects in our Galaxy and beyond: positions, distances, motions, brightnesses, colours, and even chemical compositions for millions of stars. After a brief review of the history and technology of this unique mission, I will focus on some of its many achievements and outline what can be expected from the mission in coming years. Although the satellite is no longer observing the sky, the results published until now are only based on a quarter of the observations that have been acquired, and the data processing consortium will be busy for at least five more years before the final data are released. Among the achievements thus far are the discoveries of the remnants of the last major galaxy that merged with the Milky Way 10 billion years ago, of a massive black hole in the solar neighbourhood, and the measurement of the curvature of the Sun's orbit in the cosmological frame.

Talk starts 15:15, coffee available from 15:00.