First data from Euclid space telescope reveals 26 million galaxies — and another 1.4 billion are on the way

The European Space Agency (ESA) has just released the first batch of data from the groundbreaking Euclid space telescope, which was built to study the mysteries of dark matter and dark energy throughout the universe.

The survey data, released March 19, includes initial scans of three regions that Euclid will observe regularly, as well as detailed classifications of more than 380,000 galaxies — a mere 0.4% of the galaxies scientists expect to catalog over the mission's planned six-year lifespan.

"With the release of the first data from Euclid's survey, we are unlocking a treasure trove of information for scientists to dive into and tackle some of the most intriguing questions in modern science," Carole Mundell, ESA's director of science, said in a statement.

Euclid, which launched in July 2023 and began collecting data in February 2024, aims to map the large-scale structure of the universe. Understanding this structure through the shapes, sizes and distribution of galaxies could help scientists determine the nature of dark matter and dark energy — two mysterious phenomena that together make up an estimated 95% of the universe but do not interact with light and so cannot be studied directly.

"The full potential of Euclid to learn more about dark matter and dark energy from the large-scale structure of the cosmic web will be reached only when it has completed its entire survey," Clotilde Laigle, a Euclid Consortium scientist at Institut d'Astrophysique de Paris, said in the statement. "Yet the volume of this first data release already offers us a unique first glance at the large-scale organization of galaxies, which we can use to learn more about galaxy formation over time."

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The March 19 release includes a single scan of each of the deep-field regions, three areas of the sky that Euclid will revisit multiple times to observe far into the universe. In these initial images, the telescope captured 26 million galaxies, the most distant of which are 10.5 billion light-years away. (A light-year is the distance light can travel in one year — roughly 5.9 trillion miles or 9.5 trillion kilometers.)

"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," Valeria Pettorino, Euclid project scientist at ESA, said in the statement. "Just think of the discoveries that await us."

Over the course of its planned mission, Euclid will likely capture images of 1.5 billion galaxies, sending about 100 gigabytes of data back to Earth each day. To process this tsunami of information, Euclid scientists are turning to artificial intelligence (AI). Last year, nearly 10,000 volunteers with citizen science project Galaxy Zoo helped train the "ZooBot" AI algorithm to recognize various features of galaxies, such as spiral arms, in early Euclid images.

"We're looking at galaxies from inside to out, from how their internal structures govern their evolution to how the external environment shapes their transformation over time," Laigle said in the statement. "Euclid is a goldmine of data and its impact will be far-reaching, from galaxy evolution to the bigger-picture cosmology goals of the mission."