The Euclid space telescope, launched by the European Space Agency (ESA) in 2023 to explore the dark universe, has made a stunning discovery: a perfect Einstein ring encircling the center of the NGC 6505 galaxy. This unexpected find, captured during the telescope’s early observations, offers a remarkable example of gravitational lensing, a phenomenon first predicted by Albert Einstein’s general theory of relativity.
This newly discovered Einstein ring was formed when light from a distant galaxy, located 4.42 billion light-years away, was bent and magnified by the gravity of the foreground galaxy, NGC 6505, which lies a mere 590 million light-years from Earth—a relatively short distance in cosmic terms. While NGC 6505 has been known to astronomers for over a century, the existence of the bright gravitational lens around its center had remained undetected until Euclid’s powerful instruments revealed it.
Einstein Rings: A Rare Window into the Cosmos
Einstein rings are among the rarest and most scientifically valuable gravitational lensing events. They occur when a distant background galaxy, a foreground lensing galaxy, and an observer on Earth are perfectly aligned, creating a circular halo of light around the nearer galaxy. These cosmic lenses act as natural magnifying glasses, allowing astronomers to observe faraway galaxies that would otherwise be invisible.
“An Einstein ring is an example of strong gravitational lensing,” explains Conor O’Riordan, a researcher at the Max Planck Institute for Astrophysics and lead author of the first scientific paper analyzing the ring. “All strong lenses are special, because they’re so rare, and they’re incredibly useful scientifically. This one is particularly special, because it’s so close to Earth and the alignment makes it very beautiful.”
According to a recent study published in Astronomy & Astrophysics, the discovery of this Einstein ring not only provides a spectacular visual confirmation of Einstein’s predictions but also offers critical insights into the influence of dark matter and the expansion of the universe. By analyzing the way light is bent around NGC 6505, researchers hope to refine existing models of cosmic structure formation and gain a deeper understanding of the fundamental forces shaping the universe.

Why Was This Einstein Ring Never Seen Before?
NGC 6505 has been observed by astronomers for over a century—it was first cataloged in 1884—yet no one had previously detected this gravitationally lensed ring. This highlights the unprecedented sensitivity and resolution of Euclid, which is designed to peer deeper into the universe than most ground-based telescopes.
“I find it very intriguing that this ring was observed within a well-known galaxy, which was first discovered in 1884,” says Valeria Pettorino, ESA Euclid Project Scientist. “The galaxy has been known to astronomers for a very long time. And yet this ring was never observed before. This demonstrates how powerful Euclid is, finding new things even in places we thought we knew well.”
Euclid’s mission is not just about finding rare gravitational lenses—its primary goal is to map billions of galaxies across a third of the sky, creating the most detailed 3D map of the universe ever constructed. It is expected to uncover 100,000 strong gravitational lenses, a significant leap from the fewer than 1,000 known today.
A Glimpse into the Future of Euclid’s Mission
The discovery of this stunning Einstein ring so early in the mission is a promising sign of what’s to come. Euclid’s advanced instruments allow it to detect subtle distortions in the shapes of galaxies, revealing the influence of dark matter and dark energy on the cosmos. These observations will help astronomers answer some of the most profound questions in astrophysics:
- What is dark matter made of, and how does it shape the universe?
- How has the universe expanded over time, and what role does dark energy play in this process?
- Are there hidden structures in space that we have yet to uncover?
While this Einstein ring is a spectacular discovery, Euclid’s main scientific focus is on weak gravitational lensing, where background galaxies appear mildly stretched or displaced due to cosmic structures. To detect these small distortions, scientists will need to analyze data from billions of galaxies over the coming years.
“Euclid is going to revolutionize the field, with all this data we’ve never had before,” adds Conor O’Riordan. With its extensive sky survey and precision imaging, the telescope is expected to reveal cosmic phenomena on an unprecedented scale, helping astronomers piece together the story of the universe’s evolution.
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