The European Space Agency has released observations of more than 900 million galaxies from its Euclid space telescope, giving astronomers an enormous new dataset for investigating the structure and evolution of the universe.
Announced on November 12, 2026, the release, called DR1-Foundation, contains approximately 1.7 petabytes of data collected over roughly 13 months. It covers about 1,900 square degrees of sky, equivalent to the apparent area of 9,500 full Moons.
According to ESA's official announcement, the observations represent approximately 14% of the sky area Euclid is expected to survey during its six-year mission. The release is a major step toward building a detailed three-dimensional map of the cosmos, although that map is not yet complete.
What Euclid's New Data Release Contains
DR1-Foundation is the mission's first major data release since Euclid launched in July 2023. It brings together raw observations, calibrated images, astronomical catalogs and measurements of light from distant objects.
The newly available material includes:
- More than 900 million galaxies identified across the surveyed regions.
- Approximately 15,000 strong gravitational-lensing candidates, where foreground mass appears to distort light from more distant objects.
- More than 60 million quasar candidates, potentially including the exceptionally bright centers of distant galaxies.
- Spectra from more than 160 million sources, providing information that scientists can use to investigate celestial objects and estimate distances.
- About 1.7 million gigabytes of data from the mission's wide-area survey observations.
These figures describe different categories of observations and measurements, so they should not be added together as a single count of distinct objects.
The scale represents a substantial expansion from Euclid's earlier public releases, which included observations spanning approximately 60 square degrees. Researchers now have access to a much larger area of sky, increasing their ability to identify unusual galaxies, distant clusters and rare gravitational-lensing systems.
The release also includes extensive astronomical mosaics assembled from observations in visible and near-infrared light. These provide detailed views of galaxies and cosmic structures across large regions of the sky.
How Euclid Is Building a Three-Dimensional Map of the Universe
Ordinary astronomical images show where objects appear in the sky, but understanding the universe's structure also requires information about their distances.
Euclid combines high-resolution imaging with spectroscopy, a technique that separates incoming light into different wavelengths. By examining recognizable features in a galaxy's spectrum and how those features have shifted, astronomers can estimate its redshift and investigate its distance.
As explained in ESA's explanation of Euclid spectroscopy, these measurements help researchers study the positions and properties of distant celestial objects.
Combining sky positions with distance estimates allows scientists to reconstruct the distribution of galaxies in three dimensions. The resulting maps can reveal clusters, filaments and enormous relatively empty regions that together form what astronomers call the cosmic web.
This structure developed as gravity influenced the distribution of matter over billions of years. Studying its shape and evolution can help scientists test models describing how the universe formed and expanded.
However, the newly released observations are the foundation for those investigations. They are not equivalent to a completed three-dimensional map or a final measurement of the universe's cosmological properties.
Why Gravitational Lensing Matters for Dark Matter Research
One of the most scientifically valuable parts of the release is its collection of approximately 15,000 strong gravitational-lensing candidates.
Gravitational lensing occurs when the gravity of a massive foreground object bends the path of light traveling from a more distant source. Depending on the alignment and distribution of mass, the background object can appear stretched into arcs, magnified or reproduced as multiple images.
These distortions offer an important way to investigate dark matter, the invisible component of matter whose gravitational influence can be measured even though it does not emit detectable light.
By studying the shapes and positions of gravitationally lensed images, astronomers can estimate how mass is distributed within foreground galaxies and clusters. Comparing those estimates with the visible matter helps researchers investigate the contribution of dark matter.
ESA describes the new collection as the largest catalog of strong gravitational lenses assembled to date, including uncommon configurations that were previously difficult to find.
Importantly, the approximately 15,000 objects are lensing candidates. Their classification and scientific interpretation require further analysis. The size of the catalog does not mean scientists have confirmed every system or determined what dark matter is made of.
What the Data Could Reveal About Dark Energy
Euclid's other major scientific objective is to investigate dark energy, the name given to the unknown cause associated with the universe's accelerating expansion.
Scientists can study that expansion by examining how galaxies are distributed across cosmic distances and how their clustering has changed over time.
Dark matter influences the growth of cosmic structures through gravity, while cosmic expansion affects how those structures evolve. Precise observations of galaxy positions, distances and gravitational lensing can therefore help researchers compare competing cosmological models.
Euclid is designed to combine several complementary approaches, including galaxy clustering and weak gravitational lensing. Unlike the dramatic arcs associated with strong lensing, weak lensing produces tiny statistical distortions in the apparent shapes of large numbers of distant galaxies.
Analyzing those subtle distortions can help scientists reconstruct the distribution of matter across enormous cosmic regions.
DR1-Foundation provides essential observational material for future work, but it does not announce a definitive explanation for dark energy or establish that existing cosmological theories are incorrect.
What Scientists Still Need to Verify
The release's enormous scale creates opportunities for discovery, but the distinction between an astronomical observation and a confirmed scientific result remains important.
For example, a quasar candidate may be identified from its observed characteristics without having the same level of confirmation as an object studied through detailed spectroscopy. Similarly, a possible gravitational lens must be evaluated before its physical properties can be reliably interpreted.
Measurements of cosmic distances and mass distributions also depend on observational quality, calibration procedures and analytical methods. Researchers must account for uncertainties and potential selection effects when using these catalogs to test cosmological models.
According to the Max Planck Institute for Astronomy, the new release gives researchers access to an exceptionally large collection of objects, including rare systems that were difficult to study using earlier datasets.
That scientific potential is substantial, but individual discoveries, measurements and interpretations still require careful validation.
What Comes Next for Euclid
ESA plans to follow DR1-Foundation with the complete first major data release, currently scheduled for mid-2027.
That next release is expected to add higher-level scientific products, including information for galaxy-clustering and weak-lensing studies. These measurements will help researchers examine the relationship between visible galaxies, the underlying distribution of matter and the universe's expansion history.
The mission's longer-term objective is to survey a vast portion of the extragalactic sky and trace cosmic structures across billions of years.
As Reuters reported, the release represents an important milestone in that effort, while much of the mission's most consequential cosmological analysis remains ahead.
For now, Euclid's achievement lies in making an extraordinary volume of astronomical evidence available for investigation. Its newly released observations provide scientists with a much broader view of the cosmic web and the distant galaxies that inhabit it, setting the stage for more precise tests of how the universe evolved.
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