Sometimes, the universe seems to be playing abstract art, but instead of paint and a brush, it uses gravity and light. Recently, a European telescope, with NASA’s participation, recorded a structure so symmetrical and rare that it left astronomers speechless. But this isn’t just a story about cosmic beauty. It’s also about cutting-edge science, predictions made almost a century ago by Einstein, and the chance to finally decipher mysteries like dark matter and the expansion of the universe.
From Einstein’s notebooks to the cosmos
In the early 20th century, Albert Einstein was already investigating how light bends when it passes near massive objects. In 1912, he scribbled calculations on the subject in his own notebooks. A few years later, in 1924, Russian physicist Orest Khvolson suggested the idea that celestial bodies could act as giant lenses. Then, in 1936, Einstein published a short article in the journal Science describing how this phenomenon could create rings of light around distant stars or galaxies.
Interestingly, he himself believed that no one would be able to observe this in practice. After all, it would require a near-perfect alignment between a distant source, a massive object in the middle, and us, the observers. What seemed unlikely, however, turned out to be one of the most fascinating effects predicted by his theory of general relativity: gravitational lensing. Today, almost 90 years later, this modest hunch has been transformed into breathtaking images.
Euclid’s first gift: A perfect Einstein Ring hidden in the dark
And this is where the star of the show came in: the Euclid telescope, launched in 2023 by the ESA in partnership with NASA. During its initial testing phase in September 2023, scientists received images that were still deliberately out of focus. Even so, astronomer Bruno Altieri noticed something unusual: a luminous circle hidden around a well-known galaxy, NGC 6505, located 590 million light-years away.
Days later, with new observations, the circle revealed itself clearly and perfectly. It was an Einstein Ring. This was only possible because the galaxy NGC 6505, which is relatively “close” in cosmic terms, acts as a gravitational lens. And behind it, 4.42 billion light-years away, lies a much more distant, still unnamed galaxy. It was then that the gravity of the foreground galaxy distorted the light from the background galaxy, forming a nearly perfect ring of light around it. Remembering that this is just one of Einstein’s many predictions, another worth highlighting is this strange force in the universe.
Einstein’s rings aren’t just art — they’re blueprints of the universe
What could be just a beautiful image is, in fact, a cosmic laboratory. Einstein rings are extremely rare; it’s no wonder that fewer than a thousand have ever been clearly observed, and they offer valuable scientific data. Some of the things we can learn from them are:
Dark matter: Even though it’s invisible, it contributes to the bending of light. This means each ring helps map where dark matter is hidden.
Dark energy: The mysterious force that accelerates the universe’s expansion can be studied by observing how the space between galaxies stretches.
Distant galaxies: The ring acts as a natural lens, magnifying and revealing details otherwise impossible to capture.
Euclid’s main objective is not just to find perfect rings, but to analyze the more subtle effect of “weak lensing,” when billions of galaxies appear slightly distorted. The mission will map more than a third of the sky, creating the largest 3D map of the universe ever made. It is estimated that it will identify around 100,000 strong gravitational lenses, multiplying what we know today by a hundred. A role that reminds us very much of another famous telescope, the James Webb, which detected more than 800,000 galaxies in the darkness.