What just happened? The European Space Agency’s Euclid mission released its first batch of survey data this week, providing a glimpse of hundreds of thousands of galaxies in diverse shapes and sizes, as well as numerous galaxy clusters, active galactic nuclei, and transient phenomena like supernovae and gamma-ray bursts. The data covers a substantial area of the sky in three mosaics, showcasing the mission’s capability to explore the large-scale organization of galaxies within the cosmic web.

“Euclid shows itself once again to be the ultimate discovery machine. It is surveying galaxies on the grandest scale, enabling us to explore our cosmic history and the invisible forces shaping our Universe,” said ESA’s Director of Science, Prof. Carole Mundell. She added that this data release unlocks a treasure trove of information for scientists to tackle some of the most intriguing questions in modern science.

In just one week of observations, Euclid has identified 26 million galaxies, the farthest located up to 10.5 billion light-years away. These deep fields also contain a small population of bright quasars, some of which are visible from even greater distances. Over the coming years, Euclid will revisit these regions tens of times, capturing many more distant galaxies and making these fields truly ‘deep’ by the end of the mission in 2030.

The initial glimpse of 63 square degrees of the sky previews the scale of Euclid’s grand cosmic atlas, which will eventually cover one-third of the entire sky – 14,000 square degrees – in high-quality detail.

“We will observe each deep field between 30 and 52 times over Euclid’s six-year mission, each time improving the resolution of how we see those areas, and the number of objects we manage to observe,” said Valeria Pettorino, ESA’s Euclid project scientist. “Just think of the discoveries that await us.”

Galaxies of various shapes captured by Euclid

Euclid’s high-resolution Visible Imaging System (VIS) and near-infrared instrument (NISP) are crucial for measuring galaxy shapes and distances, respectively, providing insights into the large-scale organization of galaxies within the cosmic web. This is essential for understanding dark matter and dark energy, which comprise about 95 percent of the universe.

Euclid is expected to capture images of over 1.5 billion galaxies, generating around 100 GB of data daily. Combining AI algorithms and citizen science is vital when analyzing this vast dataset. “We’re at a pivotal moment in terms of how we tackle large-scale surveys in astronomy,” said Mike Walmsley, a Euclid Consortium scientist. “AI is a fundamental and necessary part of our process in order to fully exploit Euclid’s vast dataset.”

Strong gravitational lenses captured by Euclid

Euclid is also a powerful tool for studying gravitational lensing, a phenomenon where light from distant galaxies is distorted by foreground matter. The mission has already identified 500 strong lens candidates, most of which were previously unknown. Euclid aims to capture thousands more such lenses over its mission by combining AI models with citizen science and expert vetting.

The mission’s first cosmology data will be released in October 2026.