Euclid mission reveals spectacular new space discoveries

Posted on 19 March 2025 • Science, maths, computing and technology

New data from a satellite one million miles from Earth has helped UK scientists, including those from The Open University (OU), shed light on how mysterious forces shaped the evolution of the Universe.

The release of the first survey data from the European Space Agency’s pioneering Euclid satellite – made public today – has led to a flurry of scientific advances that further our understanding of the cosmos.

Launched in July 2023, Euclid is mapping the Universe with unprecedented precision and accuracy. By examining more than one billion galaxies over six years, this groundbreaking space telescope aims to explore two of astronomy’s biggest mysteries: dark matter and dark energy.

Despite covering less than 0.5 per cent of the complete study area, the data is already proving to be invaluable for UK scientists.

The Euclid consortium, including Stephen Serjeant and Ruby Pearce-Casey at the OU, combined the power of citizen scientists and machine learning algorithms to sift through the more than one million galaxies seen in Euclid’s latest data, searching for strong gravitational lenses.

These phenomena occur when massive objects, such as galaxies, distort space-time so much that they warp the light from objects behind them into rings or arcs.

Such lenses are incredibly rare – researchers liken it to searching for needles in a haystack – but the team has identified 500 strong lens candidates.

Rarer still are systems which contain two galaxies being lensed by the same object. Four of these have been spotted and will help astronomers understand the shape and structure of the Universe.

Prof. Stephen Serjeant said:

“Dark matter has only ever been detected by its gravitational effects. Euclid’s avalanche of new gravitational lenses show these effects very clearly, warping the passage of light and telling us where the dark matter is lurking. This is a treasure trove that we hope will reveal something about what this mysterious matter is made of.”

PhD student Ruby Pearce-Casey added:

 “Searching for these warps in spacetime is a tricky needle-in-a-haystack problem. Fortunately, we have machine learning models trained on a hundred million galaxy classifications by human volunteers, which I fine-tuned to crack the problem, and which has been further refined in these new Euclid results. We still need humans to check what the machines found, but the problem of finding these rare and beautiful warps with Euclid is now tractable.”

In addition to leading some of the first scientific papers to come from this data, the UK has played a key role in the development of Euclid since its inception. University College London’s Mullard Space Science Laboratory (MSSL) led the production of Euclid’s visible instrument (VIS), a powerful camera used to capture visible light from distant galaxies, in which the OU’s Centre for Electronic Imaging have made crucial contributions.

Elsewhere, a partnership of seven UK universities contributed strongly to the Science Ground Segment, which receives the initial data from the Euclid satellite and transforms it into data that scientists can work with instantly.

For more information about the Euclid mission in the UK visit: https://eucliduk.net

Additional Euclid Resources:

Euclid Consortium Webpages: https://www.euclid-ec.org/

ESA Euclid Resources: https://www.esa.int/Science_Exploration/Space_Science/Euclid

Header image:

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/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi