Introduction

On March 19, 2025, the European Space Agency's (ESA) ambitious Euclid mission made waves in the astronomical community by releasing its first batch of survey data, providing a tantalizing preview of its deep field observations. This initial data reveals a breathtaking array of hundreds of thousands of galaxies, showcasing their diverse forms and their intricate organization within the cosmic web.

The data encompasses vast areas of the sky depicted in three expansive mosaics, illuminating galaxy clusters, active galactic nuclei, and transient cosmic phenomena. Notably, this release includes the first-ever classification of over 380,000 galaxies and 500 promising candidates for gravitational lensing, achieved through a groundbreaking combination of artificial intelligence (AI) and citizen science efforts. "Euclid is proving to be the ultimate discovery machine," stated Prof. Carole Mundell, ESA’s Director of Science. "This data unlocks a treasure trove for scientists eager to explore the Universe's most profound questions."

In just one week of observations, Euclid managed to catalog an astonishing 26 million galaxies, with some located as far as 10.5 billion light-years away. As the mission progresses, Euclid will revisit these fields repeatedly, capturing a growing wealth of data and ensuring that the final results, expected by 2030, will be a definitive cosmic atlas covering one-third of the sky—an area of 14,000 square degrees with unrivaled detail.

Exploring the Cosmic Web and Galaxy Formation

The preliminary data from the 63 square degrees observed—more than 300 times the total area of the full Moon—already hints at the remarkable potential of Euclid's mission. Valeria Pettorino, ESA's Euclid project scientist, emphasized the importance of these observations, stating, "The depth of our data will allow us to examine galaxy shapes, their formation processes, and much more. Each deep field will be surveyed multiple times throughout the mission, enhancing the resolution of our findings."

To understand the mysteries of the Universe, Euclid utilizes high-resolution imaging visible instruments (VIS) and near-infrared instruments (NISP) to measure billions of galaxies’ shapes and distances accurately. This exploration is crucial for unraveling the nature of dark matter and dark energy, believed to comprise approximately 95% of the Universe, alongside ordinary matter that forms galaxies and structures.

Harnessing AI and Citizen Science

Euclid is set to capture images of over 1.5 billion galaxies throughout its six-year mission, generating around 100 GB of data daily. Managing and analyzing such monumental datasets poses significant challenges that are being addressed through AI algorithms and the participation of thousands of citizen scientists. Mike Walmsley, a scientist involved in this endeavor, highlighted the revolutionary impact of AI: "We expect to deliver cutting-edge science much more rapidly than with previous surveys."

A landmark achievement from this collaborative effort is the initial catalogue of 380,000 galaxies, classified using the ‘Zoobot’ AI algorithm. Human volunteers meticulously taught the AI to recognize unique galaxy features, enabling unprecedented classification and analysis prowess.

Unraveling Gravitational Lensing

One of Euclid's exciting scientific tools is the exploration of gravitational lensing, which occurs when light from distant galaxies is bent by the gravitational influence of foreground galaxies and dark matter. The mission's AI-assisted efforts have already identified 500 candidates for strong lensing, leading to potential insights into the dark matter distribution around galaxies.

Looking ahead, Euclid is projected to identify up to 100,000 galaxy-galaxy strong lenses by the mission's completion, vastly expanding the current catalog of known lensing phenomena. This will not only enhance our understanding of dark matter but will also help build a three-dimensional map of its distribution over cosmic history.

Conclusion: A New Era in Cosmic Discovery

The unfolding journey of the Euclid mission promises to revolutionize our understanding of the Universe, bridging gaps in knowledge surrounding galaxy formation and the mysterious forces that govern cosmic evolution. As we stand on the brink of this new era in astronomy, the insights garnered from these data releases will echo through scientific communities for generations to come. With every passing day, Euclid draws us closer to solving the enigmatic puzzles of our existence and the far reaches of the cosmos. Stay tuned for more groundbreaking discoveries!