Gaia is an astrometry satellite of the European Space Agency. Built by Airbus, it was launched in December 2013 at Lagrange point number 2, nearly 1.5 million kilometers from Earth, in the opposite direction to the Sun. From this position, it can cover the entire sky and observe and measure all visible sources.
This satellite was designed to provide the largest and most accurate 3D map of our galaxy ever made by carrying out the largest possible census of the bodies of our Galaxy. When the mission is decided, in 2006, the goal of Gaia is to determine the position, the color and the movement clean of at least a billion stars and a few million more stars.
In June 2022, the European consortium in charge of processing Gaia data, the DPAC, made public the third dataset of the mission, the DR3, which corresponds to the first publication of the complete catalog of the mission. On this date, Gaia thus provided with unprecedented precision the position in the Galaxy of nearly 1.7 billion stars, i.e. nearly 1% of all the stars in the Milky Way. Thanks to the various instruments on board, the kinematics of a very large number of these stars is also determined as well as their physical properties such as their surface temperature and their chemical composition. Indeed, for each star that it can detect in the Galaxy, Gaia is able to measure its position and its movement, each time in three dimensions, its color as well as its physical and even chemical properties for the brightest.
From Hipparcos to Gaia
Gaia takes over the mission Hipparcos of the European Space Agency (ESA) which was the first space mission to measure positions, distances, movements, brightness and star color. Between 1989 and 1993, Hipparcos mapped some 120,000 more stars with the parallax method, between 1989 and 1993. Gaia’s measurements are 200 times more accurate than those of Hipparcos.
The catalogs produced by Gaia will serve all areas of theastrophysics including galactic and stellar physics, reference systems, black matter, the solar system and fundamental physics or the extrasolar planets. They will therefore have very significant impacts with scientific advances and major discoveries expected but also a whole bunch of astronomical manuals to be rewritten…
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