03-23-2025

Euclid captures 26 million galaxies in vivid deep field photos

Earth.com staff writer

The European Space Agency (ESA) has unveiled the first survey data from its Euclid mission. The images feature a spectacular collection of galaxies, clusters, and deep cosmic fields.

This first, massive Euclid data release previews what will soon become one of the largest cosmic maps ever created.

Three deep field mosaics highlight hundreds of thousands of galaxies. Their shapes, brightness, and distributions offer a rich visual of the cosmic web.

Each observation captures active galactic nuclei and rare, short-lived celestial events.

These glimpses already provide hints about the unseen forces shaping our Universe.

Euclid maps 26 million galaxies

The Euclid mission mapped 63 square degrees of galaxy-filled sky in just one week.

That area equals 300 full Moons. It captured more than 26 million galaxies, including quasars up to 10.5 billion light-years away. The plan is for Euclid to scan each of the three deep regions 30–52 times before 2030.

*This image shows examples of galaxies in different shapes, all captured by Euclid during its first observations of the Deep Field areas. Credit: ESA*

The final sky map will cover one-third of the sky, around 14,000 square degrees.

These repeat passes will build an incredibly detailed 3D cosmic atlas that will help researchers explore how galaxies formed and how dark matter shaped their journey.

“We are unlocking a treasure trove of information for scientists to dive into,” stated Professor Carole Mundell, director of science at the European Space Agency (ESA).

Euclid reveals galaxy web structure

Each new observation sharpens our view of the universe’s large-scale structure.

Filaments of normal and dark matter stretch across space like a vast web. These filaments are where galaxies formed and evolved.

Euclid’s visible and near-infrared instruments offer precision in measuring the shapes and distances of these galaxies.

*This image shows an area of Euclid’s Deep Field South. The area is zoomed in 70 times compared to the large mosaic. Credit: ESA*

“Just think of the discoveries that await us,” noted Valeria Pettorino, an astrophysicist who works on the Euclid Project.

ESA scientists expect these images to refine our understanding of dark matter and dark energy. Together, these two invisible components make up 95% of the cosmos.

Classifying galaxies by shape and features

Euclid’s massive galaxy dataset requires fresh strategies. Every day, it sends back 100 GB of data.

Scientists use AI models and citizen science to process this flood of information. A key result is a new catalogue of over 380,000 galaxies classified by shape and features.

“AI is a fundamental and necessary part of our process,” noted Mike Walmsley, a Euclid Consortium scientist based at the University of Toronto, Canada, who has been heavily involved in astronomical deep learning algorithms for the past decade. .

The Zoobot algorithm, trained by nearly 10,000 volunteers, now classifies galaxies by traits like spiral arms and mergers. This first catalogue is just 0.4% of what Euclid is expected to deliver.

Gravitational lenses reveal hidden matter

When light travels to us from faraway galaxies, it doesn’t always move in a straight line. If it passes through matter – like a galaxy or a cluster of galaxies – on the way, the light gets bent.

This bending is called gravitational lensing. It’s a natural effect caused by gravity and helps scientists detect dark matter, which we can’t see directly.

Using artificial intelligence and help from human volunteers, Euclid has already found 500 possible examples of strong gravitational lenses. Most of these had never been seen before.

*This image shows examples of gravitational lenses that Euclid captured in its first observations of the Deep Field areas. Credit: ESA*

By the end of the mission, it is anticipated that Euclid will find about 100,000 strong lenses. That’s a hundred times more than we currently know.

Each one gives scientists a powerful tool to study how dark matter is spread out across the Universe and how galaxies are shaped by it.

“We are combining the strengths of Euclid, AI, citizen science, and experts into a single discovery engine,” said Pierre Ferruit, ESA’s Euclid mission manager.

What’s next for the Euclid mission

By March 2025, Euclid had already scanned 2,000 square degrees of the sky, packed with galaxies. That’s about 14% of its total planned survey. This work is just the start.

The mission will share its first full set of cosmology data in October 2026. That upcoming release will include many repeated observations of three special regions called deep fields.

These repeated scans will give scientists a clearer, more detailed view of those distant parts of the Universe.

Euclid launched in July 2023. It began regular science work in February 2024. ESA built the spacecraft with support from NASA and companies like Thales Alenia Space and Airbus.

The mission is backed by the Euclid Consortium, a global team of over 2,000 scientists from 15 countries.

You can now explore the first deep field images through the ESASky platform. This is just the beginning. Euclid will continue to uncover the hidden structure of the cosmos.

Details of the latest Euclid Project images are available in this ESA press release.

Image Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by M. Walmsley, M. Huertas-Company, J.-C. Cuillandre

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