On 12 November 2026, the European Space Agency released the first major data set from the Euclid space telescope. The release, called DR1-Foundation, includes observations spanning roughly 13 months and covers a patch of sky about 1900 square degrees in area — equivalent to the area of nearly 9500 full moons. It captures the light of more than a billion objects, among them over 900 million galaxies. The volume of information amounted to 1,7 million gigabytes. This is only about 14 percent of the area the telescope plans to survey over its entire six-year mission, yet scientists already have key fragments for building the most detailed three-dimensional map of the Universe.
Euclid launched in July 2023 and operates at the Lagrange point L2, one and a half million kilometres from Earth. Its task is to study the dark Universe: dark matter, dark energy and the cosmic web, along whose filaments visible matter is distributed. Galaxies cling to the dense nodes of this invisible network, formed predominantly by dark matter. To understand how it is structured and how the cosmos expands, precise measurements of distances and masses on enormous scales are needed. Euclid was created precisely for this.
The new release demonstrates the telescope's capabilities as a wide-field survey instrument. Among the data are about 15 thousand strong gravitational lens candidates. This is the largest such catalogue in the entire history of observations, exceeding all previous ones combined. Strong lensing occurs when a massive foreground galaxy distorts and magnifies the light of more distant objects. Such systems make it possible to "weigh" galaxies together with their dark matter and to study the expansion of the Universe. Previously they were found one at a time; now scientists can study them as an entire population. Machine-learning algorithms and thousands of volunteers helped in the search through the Space Warps project on the Zooniverse platform.
In addition, the data contain more than 60 million quasar candidates — bright nuclei of distant galaxies where matter falls onto supermassive black holes. Some of them date from an era when the Universe was only about five percent of its present age. Spectra have been obtained for more than 160 million sources. By splitting light into a "rainbow", scientists determine distances to galaxies from characteristic lines, primarily hydrogen, and are beginning to build up the three-dimensional structure of the cosmic web.
Among the images are the galaxy cluster Abell 3128 at a distance of about 800 million light-years, the ring galaxy NGC 1291, the Messier 81 group and the Horologium supercluster. These images are not merely beautiful pictures. They provide the statistics needed for rare objects and for understanding how gigantic structures formed and grew.
ESA Director of Science Professor Carole Mundell noted that the release represents the largest space survey of its kind and lays the foundation for discoveries in a new field of astronomy. Mission project scientist Valeria Pettorino emphasised that previous releases covered only a few days of observations over an area of about 60 square degrees, whereas researchers now have more than a year of data over a considerably larger territory. The full Data Release 1 is expected in mid-2027 and will add weak-lensing measurements that will complete the picture.
The data are already available through the Euclid Data Space platform. They include raw observations, calibrated images, catalogues and spectra. This is only the beginning. Ahead lie years of work that will make it possible to see how dark matter shapes the cosmic web and how dark energy accelerates the expansion of the Universe. Hundreds of millions of galaxies scattered across billions of light-years are already lining up into a single map. And behind each of these distant lights lies a complex story of matter, gravity and time that is gradually becoming accessible to the human gaze.
