Smart News | October 16, 2024 4:42 p.m.

See the First Section of the Largest-Ever Cosmic Map, Revealed in Stunning Detail by the Euclid Space Telescope

The final 3D atlas of the sky will help scientists study dark matter and dark energy, which make up 96 percent of the universe but remain mysterious

An area of the mosaic released by ESA’s Euclid space telescope on October 15, 2024, which is zoomed in 36 times compared to the large mosaic. ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi

Margherita Bassi

Daily Correspondent

On its mission to reveal the secrets of the “dark universe,” the Euclid space telescope has released its most detailed image yet. The wide-angle telescope built and operated by the European Space Agency (ESA) has been investigating the cosmos since it launched into space aboard a SpaceX Falcon 9 rocket on July 1, 2023.

Its mission? To create a 3D map of one-third of the sky—the largest such map ever made. This “cosmic atlas,” as it’s also called, will be the culmination of six years of observations with Euclid’s 600-megapixel camera, studying billions of galaxies up to ten billion light-years away.

The world got its first sneak peeks of Euclid’s magnificent images in November 2023 and May 2024, with the space telescope’s survey officially beginning in February of this year. These first looks only built up anticipation in the scientific community, which expressed thrill and awe when ESA officials revealed the first part of Euclid’s cosmic atlas at the International Astronautical Congress in Milan, Italy, on Tuesday.

Mosaic of Euclid observations — This mosaic capturing a section of the southern sky contains 260 observations from the Euclid space telescope gathered over the course of just two weeks. ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi

This first section is a mosaic created from 260 observations of the southern sky captured between March 25 and April 8, 2024, per a statement from the ESA. The final product is a 208-gigapixel image revealing tens of millions of stars in the Milky Way, as well as 14 million other galaxies in shocking detail. To the human eye, its area is equivalent to more than 500 times the area of the full moon as it appears in the sky.

“This stunning image is the first piece of a map that in six years will reveal more than one-third of the sky,” Valeria Pettorino, a Euclid project scientist at ESA, says in the statement. “This is just 1 percent of the map, and yet it is full of a variety of sources that will help scientists discover new ways to describe the universe.”

Euclid is nicknamed the “dark universe detective,” because it’s meant to reveal truths about little-understood phenomena such as dark energy and dark matter, which make up about 96 percent of the universe. Dark energy is hypothesized to be the cause behind the universe’s accelerated expansion. But details about these “dark” elements of the universe remain a mystery.

To shed light on these concepts, Euclid will image a wide range of galaxies. Dark matter will have bent the light from the most distant galaxies over time, so scientists could work backward from Euclid’s observations to find out where that dark matter lies. By tracing the distribution of galaxies throughout the universe’s history, the telescope can also uncover more about dark energy.

“Euclid is observing the universe in a brand new way, and it’s gonna get a gigantic census of the galaxies,” Universidad ECCI cosmologist Luz Ángela García Peñaloza tells Space.com’s Robert Lea. “Any image that reveals information about the distribution of galaxies in the large-scale structure of the universe will provide handfuls of information on the nature of the dark side of the cosmos.”

a spiral galaxy — Spiral galaxy ESO 364-G036 appears in detail, even though this view is zoomed in 600 times from Euclid's full mosaic. ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi

Astronomers can zoom into the mosaic 600 times relative to the original image and still see celestial bodies in shocking detail. The telescope resolved the structure of spiral galaxy ESO 364-G036, which is about 420 million light-years away and fills up less than 0.0003 percent of the mapped area.

Another magnificent element captured by Euclid in this first atlas section is “galactic cirrus,” a mix of galactic gas and dust that forms dim clouds between the stars within our galaxy and reflects optical light from the Milky Way. Like wispy cirrus clouds on Earth, this phenomenon appears as streaks of light blue in the image.

“Before Euclid, we would never be able to see the faint cirrus clouds in the Milky Way and pick out every star that’s illuminating them in super-high resolution,” Mat Page, lead for Euclid’s VIS (visible instrument) camera, tells the Guardian’s Nicola Davis.

a diagram of the entire cosmos, with a small yellow section toward the bottom right demonstrating what has been mapped so far — Shown against a backdrop of the entire universe, Euclid's new detailed mosaic (highlighted in yellow) makes up just 1 percent of what the telescope will capture. ESA / Euclid / Euclid Consortium / NASA; ESA / Gaia / DPAC; ESA / Planck Collaboration

Since February, Euclid has completed 12 percent of its survey. In March 2025, experts and casual enthusiasts alike can expect the reveal of 53 square degrees of the map, as well as a preview of the Euclid Deep Field areas—a detailed survey of just three patches of sky. Data from the mission’s first year will be released in 2026.

“This is just the beginning of what we will be able to see in Euclid’s lifetime,” García Peñaloza adds to Space.com. “For sure, the best is still to come! I’m positive Euclid will shed light on our understanding of the cosmic mysteries.”