On July 11, the US President Joe Biden unveiled the first image taken by the James-Webb Space Telescope. Barely a month earlier, on June 13, a more discreet statement from theEuropean Space Agency (ESA) announced the publication of the first complete catalog of the Gaia missionconcerning the Milky Way. These very different, yet complementary, instruments dramatically confirm the value of conducting observations from space. James-Webb and Gaia are both responsible for major advances, which should benefit astronomy for decades.
Since its launch in late 2013, Gaia has been systematically sifting through the sky and lists all celestial objects placed in her line of sight, objects whose distance, position, movement and chemical composition she studies. The first complete catalog resulting from the mission now makes this data available to the entire scientific community, in the form of a three-dimensional map that represents approximately 1% of the Milky Way. A small number that hides an impressive reality: the inventory of 1.8 billion stars, 500,000 asteroids, and millions of other celestial bodies, whose existence was for some until then predicted by mathematical models but not confirmed by observations, or even unsuspected. Gaia’s Investigations even extend beyond the boundaries of the Milky Waywith, among other results, the detection of one million galaxies and six million “candidate” quasars, very active galactic nuclei, located billions of light-years from Earth, the nature of which here needs to be explained. confirmed by additional data.
Astrophysicist at the Observatory of Besançon, Annie Robin is one of the specialists involved in the Gaia mission. This catalog is the most comprehensive ever on the Milky Way, and is enriched as the data is analyzed. It becomes the spatial reference system for all observatories and telescopes in the world. Like James-Webb, who aims to target small areas or certain objects precisely: if Gaia scans the sky, James-Webb approaches it in zoom mode. He is equipped with a 6.5 m diameter mirror, compared to 2.4 m for its predecessor Hubble, and is able to capture the infrared light emitted by extremely distant objects. “It is an extraordinary instrument, unbeatable in terms of precision and depth of field. » James-Webb’s performances are proven up to distances of 13 billion light yearsa journey through space and time propelling observers almost to the origins of the formation of the universe…
Each in its own orbit, Gaia, the European probe, and James-Webb, the American telescope blending Canadian and European technologies, continue their adventures in parallel. Undoubtedly, both will mark the next few years of knowledge and exciting discoveries for astronomy.
