Launched in July 2023, the Euclid mission of the European Space Agency (ESA) is currently in space scanning a third of the sky over a 6-year-period.

In September 2025 the Euclid Consortium published the largest synthetic galaxy catalogue ever built, featuring simulations of more than 3.4 billion galaxies to match Euclid’s sharp eyes.

This synthetic catalogue aims to reproduce what the Euclid telescope will be able to see and capture, mimicking the actual Universe. Overall, this catalogue features 3.4 billions of galaxies and more than 400 modelled galaxy properties, including the galaxy brightness, positions, velocities and shapes. The resulting simulation reproduces with exquisite precision the emergence of the large-scale structure of the Universe – galaxies and galaxy clusters within the network of the cosmic web that comprises both dark and visible matter.

This video shows a part of the catalogue. Through a camera movement going backwards and upwards, it shows the region of the simulation where are ‘flying’ in the next 3 videos. The dimensions of this region are 1400 million light-years × 1400 million light-years × 21 200 million light-years. The volume shown in the image represents 1/1000 of the simulated Universe.

The following three videos show a fly-through of the simulated universe, starting near our cosmic neighbourhood and moving outward toward the beginning of time:

At 00'05'' This video displays all types of galaxies in the simulation, shown in artificial colours to highlight some of their properties.

At 00'11'' Here we see only the red galaxies, which are usually older, massive systems such as elliptical or lenticular galaxies.

At 00'18'' Each point shows a clump of dark matter – an invisible substance that makes up most of the Universe’s mass. These clumps are not scattered randomly: they form clusters, long filaments, and empty regions (voids). Galaxies form inside these dark-matter structures.