A collage of 45 different shape galaxies were all captured by Euclide during its first observations of the deep field areas. Credit: Consortium/NASA ESA/Euclid/Euclid, Elaboration of the images of M. Walmsley, M. Huertas-Company, J.-C. Cuillandre
Last month, the European Space Agency (ESA) released a huge set of data from its Space Telescope Euclid. The release presented three mosaics in the deep field that sparkled with 380,000 galaxies and hundreds of examples in which the light of distant objects is bent and enlarged by the gravitational influence of the massive galaxies.
The mosaics were captured in the constellations of Fornax, Draco and Horologium. Combined, these fields are about 63 square degrees of sky, equivalent to the area of over 300 full moons, according to a press release of the ESA of 19 March. This makes them the largest contiguous areas of the sky ever observed with an optical telescope and close to infringement, says the Euclide team. In the end, the mission aims to map over a third of the sky by 2030, accumulating 14,000 square degrees. During this period, Euclid will revisit these three fields up to 52 times more.
The release of the data marks a significant step for the Euclid mission, which was launched in 2023. Its main goal is to map and observe the galaxies in cosmic time to better understand how the universe and its largest structures evolved. With the data of those galaxies, scientists hope to discover more on the nature of gravity, dark matter and dark energy.
Scientists are still performing their initial data analysis of the data. But the current version – what the Euclid team is calling a “rapid data release” – offers the greatest taste of the power of the telescope.
An extraordinary feature of this issue of data is the number of galaxies identified: 380,000. Since this is only a fraction of what the mission should observe, the Euclide team knew that the classification of these objects would require the effort of more than a handful of researchers. So last year they enrolled the algorithms of AI of automatic learning and the help of citizens’ scientists on the Galaxy Zoo platform to order the galaxies based on their appearance, whether they had spiral arms, bars and other characteristics.
Artificial intelligence scientists and citizens have also been able to reject many locations that seem to be examples of strong gravitational lens. This is when the severity of an object in the foreground is so strong that it folds the light of an object more distant behind it, an impressive and distorting the appearance of the object distant in arches or rings (also known as the Einstein rings). The collaboration found about 500 of these objects, with many other examples of weaker lenses and lighter visual distortions.
“This release of data highlights the incredible potential that we have combining the strengths of Euclid, Ai, citizens’ sciences and experts in a single Discovery engine that will be essential to face the vast volume of data returned by Euclid,” said Pierre Ferruit, director of the mission for Euclid.
Other discoveries in the new data include thousands of weak dwarf galaxies, as well as thousands of huge red galaxies with an early universe. The latter – nicknamed “Little Red Dots” – have aroused a small sensolog among the cosmologists since they were identified for the first time in the data of the James Webb Space Telescope of the NASA in 2022, since they seem too large for having formed so early in the history of the universe. (An alternative theory suggests that excess light is actually the glow of the material that wants to just outside these black holes of galaxies).
Scientists are currently working on several articles with the first cosmological results of the Euclid mission. The team plans to publish its first full version of the data in October 2026.
