The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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Gaia's camera contains three science instruments: the astrometric instrument, the blue and red photometer, and the radial velocity spectrometer. Each one uses a set of digital detectors known as charge coupled devices (CCDs) to record the starlight falling onto them. With a total of 106 CCDs, each consisting of more than eight million pixels, Gaia's camera boasts almost one billion pixels.
The astrometric instrument is devoted to measuring stellar positions on the sky. By combining all measurements of a given star during Gaia’s mission, it is possible to deduce its parallax and thus its distance, as well as the velocity of the star as it moves across the plane of the sky.
The photometric instrument provides colour information for celestial objects by generating two low-resolution spectra, one in the blue and one in the red range of the optical spectrum. These data help to determine key stellar properties such as temperature, mass, and age.
The third instrument is the radial velocity spectrometer, which reveals the speed a star is moving towards or away from us, and the speed a star rotates around its axis. The high-resolution spectra allow to determine the star’s chemical composition as well.