Euclid's New Data Release Maps a Billion Cosmic Objects in 3D

More than 300 research institutions and over 2,500 researchers now work with the data.

Why does the 3D map matter?

The map targets the "dark universe": dark energy, dark matter, and the cosmic web of galaxies and clusters. Euclid measures distances through spectroscopy—splitting galaxy light into "rainbows" that reveal how far away each object sits. Scientists can then place galaxies within the universe's 3D structure and track how it has grown.

"I am delighted and excited that we can now take another step toward understanding why the expansion of the universe is accelerating—a mystery that has challenged physics for nearly 30 years," said Jochen Weller of Ludwig Maximilian University (LMU) in Munich.

Strong gravitational lenses—where a foreground galaxy distorts light from a more distant one—let researchers "weigh" galaxies, including their invisible dark matter. Galaxy clusters, meanwhile, show how matter clumps together over cosmic time.

"Euclid doesn't just look far back in time—it does so across vast areas of the sky," said Barbara Sartoris of the JL Lagrange laboratory in Nice, who previously worked on Euclid data at LMU and MPE. "This gives us an unprecedented view of large samples of ancient galaxy clusters that were previously out of reach."

What did Germany contribute?

A lot. Frank Grupp (LMU/MPE), German Euclid project manager and the mission's optical architect, said more than 15 years of preparatory work before launch, plus over three years in orbit, are now paying off. His team's optics deliver images of outstanding quality to the ground station.

Calibration—correcting data for instrumental effects and translating it into physical quantities—is coordinated by MPIA scientists Mischa Schirmer and Kerry Paterson. "This task ranges from designing and planning the required calibration observations to characterizing the properties of the telescope and its instruments and analyzing whether these properties change over time," Schirmer explained.

Founding members Ralf Bender (LMU/MPE), Hans-Walter Rix (MPIA), and Peter Schneider (University of Bonn) shaped the mission from the start. Bender and Rix represent Germany on the Euclid Consortium Board; Schneider chairs its Editorial Board.

Processing pipelines—software that refines raw data step by step—were prepared at LMU and now run across computing centers in Europe and the U.S. "It is all the more exciting to see how the data processing pipelines developed by our team over the years are now coming together and delivering scientific results," said Maximilian Fabricius (LMU/MPE), head of the German Euclid Data Center. Hardware shortages and extreme precision demands for brightness measurements make that work harder.

What comes next?

The current release covers only about 14% of Euclid's total planned survey. The full Data Release 1, due in mid-2027, will add weak lensing measurements and calculations of how galaxies and clusters fit into the cosmic web.

"Euclid's data have the potential to write an entirely new chapter in observational astronomy," said Martin Kümmel of LMU. "Our images in the optical and the near-infrared, combined with the photometric redshifts, will lay the foundation for a vast number of exciting results."

In short: a billion objects mapped, but the dark universe puzzle is only beginning to take shape.