The astrometric satellite Gaia was launched in December 2019. After a comprehensive commissioning phase Gaia began its nominal scientific measurements in mid 2014. Gaia’s main goal is the determination of precise astrometric data for more than one billion stars in our Milky Way with extremely high precision. Gaia Data Release 1 was published in September 2016. It contains positions and magnitudes for about 1.1 billion stars. For two million stars proper motions and parallaxes could also be determined. Almost 200 scientific papers based on this catalogue were published until November 2017. The Gaia mission will also provide constraints on the distribution of dark matter in our Galaxy and the Hubble constant.