In 2025, over 1,000 volunteers searched telescope images for galaxies that bend light; they helped find 497 possible cosmic lenses

Many galaxies, located in the depths of space, have very unusual structures and shapes, such as elongated arcs, bent rings, or multiple distorted images unlike typical galaxies. The reason for the strange style is not a mirage, but the phenomenon where the gravity of a massive galaxy bends light coming from a much more distant object behind it. To identify the mentioned uncommon structures, scientists need to process a huge number of images collected through telescopes. In 2025, more than 1,000 volunteers around the world joined the Space Warps – ESA Euclid project to help scientists search through images from the Euclid Space Telescope. Their effort helped identify 497 strong gravitational lens candidates from Euclid’s early data. The Space Warps – ESA Euclid project states that volunteers contributed more than 800,000 classifications while inspecting galaxy images and helped researchers find these rare lens candidates.

Gravity turns galaxies into natural telescopes

A gravitational lens occurs when a massive object, such as a galaxy, sits between Earth and a more distant galaxy. The gravity of the foreground galaxy distorts the path of light coming from the background galaxy, causing the image of the distant galaxy to be stretched, enlarged, or even duplicated. For astronomers, these distortions are valuable. The gravitational lens is not only an unusual image, but it is a natural instrument used to look at the universe. Light bending can provide clues to the mass of galaxies, even that which is invisible. However, these lenses are extremely rare. Most galaxy images collected by telescopes do not contain them, meaning scientists must search through enormous amounts of data to find the few hidden examples.


Why computers alone cannot find every lens

The Euclid Space Telescope will take detailed pictures of vast portions of the sky. Even with the latest in computer systems, the search for the most likely candidates for lenses is still difficult. Artificial intelligence can help narrow down possible discoveries, but some images still require human judgment. Galaxies have unusual shapes, and some features can resemble gravitational lenses even when they aren’t. The Space Warps project created a way for members of the public to participate in this scientific search. The volunteers were given images of the galaxy and asked to look for any evidence of gravitational lensing, including images that might be curved or multiple images. Rather than replacing scientists, the volunteers helped complete an early stage of the research by sorting through large numbers of images and highlighting the most interesting candidates.

The search that combined humans and machines

The search was done by both human observations and computer-based methods. The first step in identifying galaxies that were more likely to contain lenses was done with the help of machine-learning systems. These images were then subjected to further scrutiny by volunteers. It was this combined approach that the Space Warps – ESA Euclid project chose, as human observers can see patterns that automated systems can miss. Citizen scientists were an important piece of the lens discovery process and helped analyze candidates from Euclid's initial observations. After volunteers reviewed the images, the best of the best were looked at in more detail by scientists. The final list included 497 possible strong gravitational lenses that required further scientific study. Each of these candidates is significant as a new window through which to examine the formation of galaxies, distribution of matter, and light in the universe.

A new role for citizen scientists

The project shows how the evolution of astronomy has changed in the era of large-scale space surveys. Modern telescopes can collect more information than small research teams can easily analyze on their own. Citizen science enables thousands of individuals to dedicate a small portion of their time to scientific endeavors that would take many more hours if done by researchers alone. A volunteer looking at a single galaxy image may seem to be performing a simple task, but thousands of those decisions together can help reveal objects that were hidden in massive datasets. For participants, they are not only learning about astronomy but also helping researchers decide which parts of the universe deserve closer examination.

What these cosmic lenses could reveal next

The discovery of hundreds of potential gravitational lenses provides astronomers a unique tool to explore otherwise unobservable regions of space. Once confirmed, these lenses can act as natural magnifying glasses, making it possible for astronomers to study distant galaxies that would normally appear too faint or too far away to study in detail.