The European Euclid probe reveals the first pages of its celestial atlas

2024-10-20 17:00:00

<img src="https://img.lemde.fr/2024/10/17/0/0/3840/2160/664/0/75/0/4505a51_1729172375189-euclid-spots-interacting-galaxies.jpg" alt="Distant galaxies photographed by the European Space Agency's Euclid space telescope.” sizes=”(min-width: 1024px) 556px, 100vw” width=”664″ height=”443″/> Distant galaxies photographed by the European Space Agency’s Euclid space telescope. ESA

In the publishing world, a common promotional practice upon the release of a book is to reveal excerpts, the “good sheets”. The European Space Agency (ESA) has just played the same game by revealing, on the occasion of the 75th International Astronautical Congress, which was held in Milan (Italy) from 14 to 18 October, the first pages of the sky atlas that its Euclid probe is currently under construction.

This first “panel” revealed by ESA covers 132 square degrees of sky, more than five hundred times the size of the Moon as we see it from Earth. No fewer than 260 observations were needed to constitute this mosaic. However, it represents only a fragment, about 1%, of what Euclid will map during his mission. The probe will focus on the entire part of the firmament not too “polluted” by our own galaxy, the Milky Way, that is, just over a third of the sky. If all goes as planned, the entire survey will be published in stages by 2030.

Invisible elements

For the moment it’s not a problem “Only 1% of paper [finale]yet it is filled with a wide variety of sources that will help scientists discover new ways of describing the Universe.comments Valeria Pettorino, an Italian astrophysicist who works on Euclid at ESA.

Read also (2023) | Article reserved for our subscribers The Euclid mission aims to probe the dark side of the Universe

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It may seem paradoxical, but the main objective of the mission is to understand two elements… which we cannot see in the images! The first is dark matter, which guarantees in particular the cohesion of galaxies: without it, the stars gathered in these groups that rotate on themselves would be expelled into the cosmos like children who do not hold on tightly to a turnstile. Dark matter is perceived through its mass, but does not interact with electromagnetic waves at all, which makes it invisible.

Second objective of the cosmologists’ investigations: dark energy, which according to theory is responsible for the accelerated expansion of the Universe and is no longer visible. Together, dark matter and dark energy amount to 95% of the contents of the cosmos (compared to just 5% of the “classical” matter we are made of). Suffice it to say, understanding their properties presents a real challenge.