Cutting-edge UK research is benefiting the European Space Agency’s Euclid mission, with new data released today (19 March) set to uncover the secrets of dark energy and matter.
The wealth of new data from the mission – described as the ultimate discovery machine – includes details of 500 galaxies that seem to experience a phenomenon known as strong lensing.
This is where light from more distant galaxies is bent around closer galaxies due to gravity, like how light is focused through a glass lens on Earth.
The way the light bends indicates the total mass, which includes both visible matter and, potentially, dark matter – so scientists can analyse this, begin to identify where dark matter is located, and understand its properties.
Euclid's data is revolutionising the study of strong lensing. New techniques using machine learning and AI have been developed to find these rare objects. Citizen science has also contributed significantly, with over 1000 volunteers participating in visual inspections.
UK Science Minister, Lord Vallance said: "The UK space sector is playing a leading role in the Euclid mission which, as this new data shows, is revealing more about the role of gravity in our Universe, and the nature of dark energy and matter. The British-made visible imager and data processing tools are central to these observations.
“The technological advances achieved in missions like this will not only benefit our understanding of the universe, but may help us to better process data here on Earth, helping us to grow our economy and support our Plan for Change.”
The Euclid mission, launched in July 2023, carries a visible imager (VIS) from the UK, funded by £37 million from the UK Space Agency. The VIS, designed and built by a UCL-led team, is a super high-resolution camera (609 million pixels), with a focal plane about the size of a large pizza box, that can take incredibly detailed pictures of the sky. It is currently observing billions of galaxies up to 10 billion light years away.
The new data release includes observations of distant regions of space, displaying hundreds of thousands of galaxies and many transient phenomena – astronomical events that are temporary or short-lived relative to cosmic history. These include supernovae (explosions of stars at the end of their life cycles), gamma-ray bursts (extremely energetic explosions observed in distant galaxies), and fast radio bursts (brief but intense bursts of radio waves from unknown sources in space).
All of this allows scientists to gain insights into the dynamic processes occurring in the universe. The release classifies over 380,000 galaxies and 500 gravitational lens candidates.
“Euclid shows itself once again to be the ultimate discovery machine. It is surveying galaxies on the grandest scale, enabling us to explore our cosmic history and the invisible forces shaping our Universe,” said ESA’s Director of Science, Professor Carole Mundell.
The ‘quick’ data release
Euclid ‘quick’ releases, such as this one, are of selected areas, intended to demonstrate the data products to be expected in the major data releases that follow, and to allow scientists to sharpen their data analysis tools in preparation. The mission’s first cosmology data will be released to the community in October 2026.
“This early data release showcases the amazing images that we will receive from the Euclid telescope. Even in this tiny area (less than 0.5% of the Euclid survey), Euclid has revealed millions of galaxies in exquisite detail," said Aprajita Verma, a Senior Researcher at the University of Oxford and Fellow of the Royal Astronomical Society (RAS).
Nestled among these galaxies are strong gravitational lenses. This rare phenomenon is seen around massive galaxies that can distort or warp space-time so much that light from objects behind them can be brought into view as rings, arcs or multiple images.
"This is exactly what has been revealed in this early Euclid data, and at a higher frequency than we’ve seen from surveys with ground-based telescopes,” added Dr Verma.
The team used a combination of machine learning with visual inspection from citizen scientists and the team to develop an efficient discovery engine.
Professor Thomas Collett, from the University of Portsmouth's Institute of Cosmology and Gravitation and a Fellow of the RAS, said: "Euclid has provided spectacular image quality across a huge area of the sky, which is critical to discovering small, rare objects. We've found 500 new strong gravitational lenses in the Euclid dataset.
"These are galaxies distorted into rings of light by the mass of another foreground galaxy. We have combined the strengths of machine learning and citizen scientists to sift out these rare objects from the millions of other galaxies in Euclid. These new lenses will allow us to make new measurements of the mysterious dark matter and dark energy that make up 95% of our Universe but which are poorly understood."
Before Euclid, astronomers had to choose between wide-field images from lower resolution telescopes like the Dark Energy Survey in Chile, or detailed zoomed-in images from telescopes like Hubble, but only on small regions. Euclid, with its 609 mega pixel camera led by the UK, combines both panoramic mode and detailed imaging. The area mapped in this release is already a significant fraction of all the sky covered by Hubble since 1990.
This innovation is transformative for strong lensing studies, which require large panoramic images to locate rare objects and detailed views to analyse them.
Professor Adam Amara, Chief Scientist at the UK Space Agency, who first proposed the idea for Euclid, said: “Previously, astronomers like me used wide low-resolution surveys to find strong lenses and then requested Hubble for follow-up observations. Now, Euclid accomplishes both tasks in one shot.
“This data release is the first clear evidence that Euclid will be a unique rare object finder (as well as an exquisite dark energy measuring machine). In terms of rare objects in the universe, I'm excited to see what 'unknown-unknowns' it will discover - it's been a long wait.”
UK scientists and institutions around the country have developed bespoke data processing tools for Euclid and are analysing the wealth of data being returned by the mission. Five key papers led by UK researchers are shared as part of this data release.
Professor Mike Lockwood, President of the Royal Astronomical Society, said: “To see UK astronomers, space scientists and engineers playing key roles in this extraordinary scientific endeavour is truly inspiring – and what’s even better is that this is just the beginning.
“We can look forward to Euclid giving us the most detailed ever 3D map of the cosmos, helping to solve the biggest cosmic mysteries – what the universe is made of, how it evolved, and what its future holds.”
The wider benefits of space science
The ripple effects of technological advances in space science extend far beyond the realm of space exploration, driving advances and growth across multiple sectors in the UK. The need for compact and efficient technology in space missions has led to advancements in miniaturisation, which benefit consumer electronics such as smartphones and laptops.
In healthcare, machine learning techniques developed for imaging technologies used in space exploration are being adapted to create more precise medical imaging techniques, potentially improving diagnosis and patient outcomes. The vast amounts of data collected by missions like Euclid are processed using advanced algorithms, which are now being used in healthcare to analyse patient data and predict disease outbreaks.
ENDS
Media contacts
Amy Lee Pierce
UK Space Agency
amy.leepierce@ukspaceagency.gov.uk
Sam Tonkin
Royal Astronomical Society
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Images and captions
Header image: Title - Strong gravitational lenses captured by Euclid
This image shows examples of gravitational lenses that Euclid captured in its first observations of the Deep Field areas.
Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by M. Walmsley, M. Huertas-Company, J.-C. Cuillandre
[Image description: A collage of fourteen by eight squares containing examples of gravitational lenses. Each example typically comprises a bright centre with smears of stars in an arc or multiple arcs around it as a result of light travelling towards Euclid from distant galaxies being bent and distorted by normal and dark matter in the foreground. In some rare cases the smearing is in a complete ring, creating a so-called Einstein Ring.]
Additional image 1: Title - Euclid Deep Field South, 70x zoom
This image shows an area of Euclid’s Deep Field South. The area is zoomed in 70 times compared to the large mosaic.
Various huge galaxy clusters are visible in this image, as well as intra-cluster light, and gravitational lenses. The cluster near the centre is called J041110.98-481939.3, and is located almost 6 billion light-years away.
Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
[Image description: A sea of galaxies of many different shapes and sizes, oriented in all directions and many with spiral arms visible. A large, nearby face-on spiral galaxy draws attention at the bottom centre of the image. Two bright stars in the centre and to the left are seen with prominent diffraction spikes. In between the two stars lie a lensed galaxy cluster, with arc-like smears surrounding the central bright galaxy cluster.]
Additional image 2:
Title: Location of Euclid Deep Fields on Gaia and Planck sky map
This graphic shows the location of the Euclid Deep Fields (yellow). This all-sky view is an overlay of ESA Gaia’s star map from its second data release in 2018 and ESA Planck’s dust map from 2014. The sky is shown in the Galactic coordinate system, with the bright horizontal band corresponding to the plane of our Milky Way galaxy, where most of its stars reside.
Credit: ESA/Euclid/Euclid Consortium/NASA; ESA/Gaia/DPAC; ESA/Planck Collaboration
[Image description: An oval image showing a projection of the night sky with the bright plane of our Milky Way galaxy running horizontally through the centre. Cloud-like features representing stars and interstellar gas and dust extend above and below the plane. Three small regions are marked in yellow, indicating the locations of Euclid’s three deep field surveys. One is above and to the left of the horizontal plane, the other two are to the bottom right. All three are located in seemingly emptier regions, in between the cloud-like features.]
Further information
Background to Euclid
The European Space Agency’s Euclid mission launched in July 2023 to map the ‘dark Universe’. It will observe two billion galaxies and create a 3D map of the universe, focusing on its structure and cosmic history.
Led by ESA and a consortium of 2,000 scientists from 16 countries, Euclid will operate for six years using two instruments: a visible imager (VIS) built in the UK, one of the largest cameras sent into space, and a near-infrared spectrometer and photometer developed in France.
The UK Space Agency’s £37m funding goes back to 2010, up to 2024, and is divided between teams at University College London, The Open University, University of Cambridge, University of Edinburgh, University of Oxford, University of Portsmouth and Durham University. All these institutions have contributed to the development and implementation of the Euclid UK Science Ground Segment (UKSGS), which runs the Euclid data analysis. Led by the University of Edinburgh, which hosts Euclid’s UK Science Data Centre (SDC-UK).
As of 19 March 2025, Euclid has observed about 2000 square degrees, approximately 14% of the total survey area (14 000 square degrees). The three deep fields together comprise 63.1 square degrees.
What's included in the Data Release
Link for journalists to receive the Q1 images from ESA: https://blogs.esa.int/forms/subscription-for-under-embargo-press-releases/
Strong Lensing Papers: These are a series of scientific papers that focus on a phenomenon called strong gravitational lensing. This occurs when a massive object, like a galaxy cluster, bends and magnifies the light from objects behind it, allowing us to see them more clearly. The papers include findings from the first data release and predictions about future discoveries.
Galaxy Clusters and Red Dots: This section introduces a catalogue of galaxy clusters with strong lensing effects and explores the search for "little red dots"—small, faint astronomical objects at great distances. These red dots are distant galaxies or star-forming regions, appearing red due to the redshift effect, where light from faraway objects stretches to longer wavelengths as it travels through the expanding universe.. They offer valuable insights into early galaxy formation.
Machine Learning and Lensing: Scientists are using advanced techniques like machine learning – a type of artificial intelligence – to identify gravitational lenses more efficiently. This approach is detailed in several papers, including the first comprehensive list of galaxies showing strong lensing.
Strong lensing and DSPL: Gravitational lensing bends light from objects behind a massive galaxy, making them appear larger and clearer. A double source plane lens (DSPL) bends light from two different distant objects, allowing scientists to measure universe properties more accurately. By studying this light bending, they learn about dark energy and the amount of matter in the universe, enhancing calculation precision. DSPLs improve cosmology by offering unique insights into fundamental universe properties.
Euclid Deep Fields
The data release will feature observations covering approximately 50 square degrees of the Euclid Deep Fields. To put it simply, this area is like a small, highly detailed patch of the sky that Euclid is examining closely, providing valuable insights into the structure and composition of our universe. These findings will pave the way for new discoveries and deepen our understanding of the cosmos.
Notes for editors
About the Royal Astronomical Society
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The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.
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