UCL News


Euclid space mission celebrates first science with sparkling cosmic views

23 May 2024

Five new views of the Universe have been released today, captured by the European Space Agency’s Euclid telescope, whose massive optical camera was designed and built by an international team led by UCL researchers.

This breathtaking image features Messier 78, a vibrant star nursery enveloped in interstellar dust.

The never-before-seen images demonstrate Euclid’s ability to unravel the secrets of the cosmos and enable scientists to hunt for rogue planets, use lensed galaxies to study mysterious matter, and explore the evolution of the Universe.

The new images are part of Euclid’s Early Release Observations. They accompany the mission’s first scientific data, also made public today, and 10 forthcoming science papers. The treasure trove comes less than a year after the space telescope’s launch, and roughly six months after it returned its first full-colour images of the cosmos.

The images, containing galaxy clusters, free-floating planets and a star-forming region enveloped in interstellar dust, were created by combining data from Euclid’s two instruments: VIS, a visible light camera, and the Near Infrared Spectrometer and Photometer (NISP), which captures light from the infrared spectrum.

Professor Mark Cropper (Mullard Space Science Laboratory at UCL), who led on designing and developing the VIS optical camera over 16 years, working with teams at UCL, Open University and across Europe, said: “These are the largest images of the Universe ever taken from space, covering large swathes of the sky in fine detail. They demonstrate Euclid’s wide-ranging potential, from discovering new planets to surveying vast clusters of galaxies.

“To achieve its core aim of better understanding dark energy and dark matter, Euclid’s measurements need to be exquisitely precise. This requires a camera that is incredibly stable, incredibly well understood, with conditions inside it needing to be controlled very carefully. The VIS camera we developed will not only contribute beautiful images, but help us answer fundamental questions about the role of dark energy and dark matter in the evolution of the Universe.”

Euclid will trace the hidden web-like foundations of the cosmos, map billions of galaxies across more than one-third of the sky, explore how our Universe formed and evolved over cosmic history, and study dark energy and dark matter, the Universe’s most mysterious components.

The images obtained by Euclid are at least four times sharper than those we can take from ground-based telescopes. They cover large patches of sky at unrivalled depth, looking far into the distant Universe using both visible and infrared light.

ESA Director of Science, Professor Carole Mundell, said: “It’s no exaggeration to say that the results we’re seeing from Euclid are unprecedented. Euclid’s first images, published in November, clearly illustrated the telescope’s vast potential to explore the dark Universe, and this second batch is no different.

“The beauty of Euclid is that it covers large regions of the sky in great detail and depth, and can capture a wide range of different objects all in the same image – from faint to bright, from distant to nearby, from the most massive of galaxy clusters to small planets. We get both a very detailed and very wide view all at once.

“This amazing versatility has resulted in numerous new science results that, when combined with the results from Euclid’s surveying over the coming years, will significantly alter our understanding of the Universe.”

While visually stunning, the images are far more than beautiful snapshots; they reveal new physical properties of the Universe thanks to Euclid’s novel and unique observing capabilities.

These scientific secrets are detailed further in a number of accompanying papers released by the Euclid collaboration, made available on arXiv (linked below), together with five key reference papers about the Euclid mission.

The early findings showcase Euclid’s ability to search star-forming regions for free-floating “rogue” planets just four times the mass of Jupiter; study the outer regions of star clusters in unprecedented detail; and map different star populations to explore how galaxies have evolved over time.

They reveal how the space telescope can detect individual star clusters in distant groups and clusters of galaxies; identify a rich harvest of new dwarf galaxies; see the light from stars ripped away from their parent galaxies – and much more. Euclid produced this early catalogue in just a single day, revealing over 11 million objects in visible light and 5 million more in infrared light. This catalogue has resulted in significant new science.

Dr Caroline Harper, Head of Space Science at the UK Space Agency, said:  “A key part of our purpose as a space agency is to understand more about the Universe, what it’s made of and how it works. There is no better example of this than the Euclid mission - we know that most of Universe is made up of invisible dark matter and dark energy, but we don’t really understand what it is, or how it affects the way the universe is evolving.  

“Science missions like Euclid generate vast quantities of valuable data for scientists across the world, and UK researchers have played a leading role in the development of the mission and in delivering these early results, less than a year after launch.”  

Introducing the images

Professor Mat Page (Mullard Space Science Laboratory at UCL), current VIS lead, said: “What is remarkable about the VIS images is just how very big they are. When you look through a microscope, you see things in amazing detail, but you can only see a tiny area; imagine that you had a new machine that let you see that kind of detail in everything on your table all at once. That’s how it feels with Euclid.

“We’re used to looking at tiny specks of the sky in superb detail with Hubble, but now we’re seeing great big areas all at once with Euclid VIS.”

Abell 2390

Euclid’s image of galaxy cluster Abell 2390 reveals around 50 000 galaxies
Euclid’s image of galaxy cluster Abell 2390 reveals around 50 000 galaxies and shows a beautiful display of gravitational lensing, depicting giant curved arcs on the sky – some of which are actually multiple views of the same distant object. Euclid will use lensing (where the light travelling to us from distant galaxies is bent and distorted by gravity) as a key technique for exploring the dark Universe, indirectly measuring the amount and distribution of dark matter both in galaxy clusters and elsewhere. Euclid scientists are also studying how the masses and numbers of galaxy clusters on the sky have changed over time, revealing more about the history and evolution of the Universe.

Euclid’s cutout view of Abell 2390 shows the light permeating the cluster from stars that have been ripped away from their parent galaxies and sit in intergalactic space. Viewing this ‘intracluster light’ is a specialty of Euclid, and these stellar orphans may allow us to ‘see’ where dark matter lies.

Messier 78

This breathtaking image features Messier 78, a vibrant star nursery enveloped in interstellar dust.
This breathtaking image features Messier 78, a vibrant star nursery enveloped in interstellar dust. Euclid peered deep into this nursery using its infrared camera, exposing hidden regions of star formation for the first time, mapping its complex filaments of gas and dust in unprecedented detail, and uncovering newly formed stars and planets. Euclid’s instruments can detect objects just a few times the mass of Jupiter, and its infrared ‘eyes’ reveal over 300 000 new objects in this field of view alone. Scientists are using this dataset to study the amount and ratio of stars and smaller (sub-stellar) objects found here – key to understanding the dynamics of how star populations form and change over time.

NGC 6744

In this image Euclid showcases NGC 6744, an archetype of the kind of galaxy currently forming most of the stars in the local Universe.
In this image Euclid showcases NGC 6744, an archetype of the kind of galaxy currently forming most of the stars in the local Universe. Euclid’s large field-of-view covers the entire galaxy, capturing not only spiral structure on larger scales but also exquisite detail on small spatial scales. This includes feather-like lanes of dust emerging as ‘spurs’ from the spiral arms, shown here with incredible clarity. Scientists are using this dataset to understand how dust and gas are linked to star formation; map how different star populations are distributed throughout galaxies and where stars are currently forming; and unravel the physics behind the structure of spiral galaxies, something that is still not fully understood after decades of study.

Abell 2764 (and bright star)

This view shows the galaxy cluster Abell 2764 (top right), which comprises hundreds of galaxies within a vast halo of dark matter.
This view shows the galaxy cluster Abell 2764 (top right), which comprises hundreds of galaxies within a vast halo of dark matter. Euclid captures many objects in this patch of sky, including background galaxies, more distant clusters, and interacting galaxies throwing off streams and shells of stars. This complete view of Abell 2764 and surroundings — obtained thanks to Euclid’s impressively wide field-of-view — allows scientists to ascertain the radius of the cluster and see its outskirts with faraway galaxies still in frame. Euclid’s observations of Abell 2764 are also allowing scientists to further explore galaxies in the distant cosmic dark ages, as with Abell 2390.

Also seen here is a very bright foreground star that lies within our own galaxy (Beta Phoenicis, a star in the southern hemisphere that’s bright enough to be seen by the human eye). When we look at a star through a telescope, its light is scattered outwards into a diffuse circular halo due to the telescope’s optics. Euclid was designed to make this scatter as small as possible. As a result, the star causes little disturbance, allowing us to capture faint distant galaxies near the line of sight without being blinded by the star’s brightness.

Dorado Group

Here, Euclid captures galaxies evolving and merging ‘in action’ in the Dorado galaxy group,
Here, Euclid captures galaxies evolving and merging ‘in action’ in the Dorado galaxy group, with beautiful tidal tails and shells seen as a result of ongoing interactions. Scientists are using this dataset to study how galaxies evolve, to improve our models of cosmic history and understand how galaxies form within halos of dark matter. This image showcases Euclid’s versatility: a wide array of galaxies is visible here, from very bright to very faint. Thanks to Euclid’s unique combination of large field-of-view, remarkable depth, and high spatial resolution, it can capture tiny (star clusters), wider (galaxy cores) and extended (tidal tails) features all in one frame. Scientists are also seeking distant individual clusters of stars known as globular clusters to trace their galactic history and dynamics.

VIS camera

The VIS (for Visible) instrument is a 609 megapixel optical camera. Its wide field of view means that, while it takes images that are nearly as sharp as the Hubble Space Telescope, it covers a much larger area of the sky – covering the same area in one day as Hubble covered over 25 years. Each image would require 300 high-definition TV screens to display. Over six years it will allow the shape of more than 1.5 billion galaxies to be measured.

The VIS camera was a pan-European project led by UCL’s Mullard Space Science Laboratory (MSSL). Its structure and calibration unit came from France, the shutter from Switzerland, and a processing unit was built in Italy. The core electronics, including its array of 36 CCDs (that convert photons into electrons), were built, tested and calibrated at MSSL. A team of MSSL experts are also supporting the operation of the VIS instrument in flight.

In addition, researchers at MSSL and UCL Physics & Astronomy are involved in processing and analysing Euclid’s data to see how it compares to mathematical models of the Universe.

Euclid Consortium

The new scientific papers were released by the Euclid Consortium. In collaboration with ESA, the Euclid Consortium has been planning, building, and is currently operating the Euclid space telescope mission. The consortium comprises more than 2,600 members, including over 1,000 researchers from more than 300 laboratories in 15 European countries, plus Canada, Japan and United States, covering various fields in astrophysics, cosmology, theoretical physics, and particle physics.



  • Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO or ESA Standard Licence.

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