Ruprecht-Karls-Universität Heidelberg

Gaia: the scientific supermission and its third data release

Gaia: the scientific supermission and its third date release

Launched by the European Space Agency (ESA) in December 2013, the Gaia Space Observatory is an astronomical observation mission that provides stellar data in unprecedented quantity and precision and which are made available to the world's astronomers for their research.

Gaia's main goal is to create a three-dimensional catalogue of billions of astronomical objects, with the greatest difficulty being the accurate measurement of their distances. In addition, Gaia tracks every star targeted with the two telescopes on board over the years. The analysis of this data allows, for example, conclusions to be drawn about the past of the Milky Way, in which our solar system is located.

The analysis of the Gaia data has already helped in recent years to take a sharper look at the evolution of our galaxy. It could be concluded that the Milky Way has repeatedly absorbed smaller star systems over the course of billions of years. There were even clear indications that a near passage of such a dwarf galaxy triggered the formation of our Sun about 4.5 billion years ago.

On average, since the publication of Gaia's second star catalogue in 2018, almost five scientific papers from virtually all fields of astronomy have been published every day, at least to a large extent based on Gaia measurements. Many astronomers speak of the Gaia revolution, which has significantly advanced astronomy in recent years. However, despite such groundbreaking work that Gaia makes possible, this important observatory could easily be overlooked by the public. Much more attention than Gaia goes to the exciting images from the Hubble Space Telescope or the space probes in our planetary system. From a scientific point of view, however, Gaia plays absolutely in the same league - at a drastically lower total cost - and after all, computer animations can also be used to visualize the initially "dry" Gaia data in an exciting and impressive way to the public.


Gaia Data Release 3 on June 13, 2022: third scientific milestone of the mission

And now it's that time again: On June 13, 2022, Gaia Data Release 3 (Gaia DR3) - the third huge catalog of measured values - was published. Astronomers all over the world were ready to download the most interesting data from the Gaia archives at exactly 12:00 noon.

And the new catalog has it all: data for more than 1.8 billion stars are included, including 1.5 billion entries with star positions, distances and stellar motions. And particularly important are 33 million data sets for stars in which Gaia was able to measure the radial velocity, i.e. the movement of the stars towards or away from us. These are especially helpful for deciphering the Milky Way's past. Until now, gaia's second catalogue for only seven million stars meant that all speed components were known.

But scientists are also waiting for completely new data products: For the first time, Gaia DR3 will also be used to publish 220 million spectra with low spectral resolution. Gaia's measuring instruments split the light of the celestial objects into its individual wavelengths. In this way, the stars can be classified and, for example, their temperatures at the star's surface can be determined. This can be achieved even more precisely with the help of a high-resolution spectrograph in the infrared on board of the satelellite.

Almost a million of these spectra make it possible to determine the abundance of chemical elements and their abundance in the outer layers of stars. These data also allow a glimpse into the past of our Milky Way: Over time, the chemical elements were created in stars that make up our Earth and the living beings on it.

In addition, the Gaia DR3 provides a large number of special catalogs with binary stars, variable stars, galaxies, quasars and asteroids in our solar system that astronomers are eagerly awaiting.

In Germany, there are mainly four institutes working on the production of the Gaia catalogues: the Leibniz Institute for Astrophysics in Potsdam, the Lohrmann Observatory of the TU Dresden, the Max Planck Institute for Astronomy in Heidelberg and the Astronomical Computing Institute at the Center for Astronomy of Heidelberg University.


Release of gaia DR3: Event at the House of Astronomy

Together with the House of Astronomy (HdA), the Astronomisches Rechen-Institut (ARI) presented the new Gaia catalogue on 13 June 2022 between 11:00 a.m. and 12:00 p.m. and gave an impression of the associated scientific revolution. A recording of the event can be viewed HERE.


Additional information

Information provided by the Gaia Group at the Astronomisches Rechen-Institut:
Information about the Gaia Data Release 3 (DR3) provided by ESA:



Prof. (apl.) Dr. Stefan Jordan (Gaia Outreach Manager in the european gaia consortium): jordan(at)





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