Imagine peering into the cosmos and witnessing the birth, growth, and transformation of over a million galaxies in just one year. Sounds like science fiction, right? But that’s exactly what the Euclid space telescope has achieved, and the revelations are nothing short of mind-blowing. Launched in July 2023, this powerhouse of a telescope has already observed a staggering 1.2 million galaxies, cataloged in its first data release in March 2025. And this is just the beginning—by the end of its 6-year mission, Euclid is expected to study tens of millions more. So, what have we learned so far? Here’s where it gets fascinating...
The European Space Agency’s Euclid mission is tackling one of astronomy’s most intriguing puzzles: why galaxies come in such diverse shapes, from majestic spirals like our Milky Way to featureless ellipticals like Messier 87. But here’s where it gets controversial: understanding these shapes isn’t just about aesthetics—it’s about unraveling how galaxies and their supermassive black holes evolve together. Yes, you heard that right. Galaxies and their black holes grow in tandem, and Euclid is giving us the clearest picture yet of this cosmic dance.
One of the most groundbreaking findings? Euclid’s data has allowed scientists to create a galactic tuning fork diagram. Think of it as a roadmap of galactic evolution, where star-forming galaxies on the right gradually transform into massive ellipticals on the left as they exhaust their gas, merge with others, and reshape their structures. And this is the part most people miss: this process isn’t just about stars and dust—it’s deeply tied to the growth of supermassive black holes at galactic centers.
Maximilian Fabricius, a scientist at the Max Planck Institute for Extraterrestrial Physics, puts it this way: ‘Euclid offers an unprecedented combination of sharpness and sky coverage—it will map the entire extragalactic sky. For the first time, we can systematically study how the shapes and central structures of galaxies relate to their formation history on truly cosmic scales.’
Here’s where it gets even more intriguing: Euclid has identified galaxies with secondary nuclei, which could merge to form supermassive black hole binaries. These binaries emit gravitational waves as they spiral toward each other, eventually colliding to create even larger black holes. Bold claim alert: this process is an inevitable outcome of galactic mergers, shaping the colossal elliptical galaxies we see today. But before that happens, there’s a brief double nuclei phase—a cosmic blink of an eye that Euclid is now capturing in unprecedented detail.
Breaking it down further: Euclid’s sensitivity has also revealed a surprising truth. The most common galaxies in the universe aren’t spirals like the Milky Way but faint, elusive dwarf galaxies. These tiny galaxies, long overlooked due to their dimness, are now thought to be the building blocks of larger galaxies. Euclid has already identified 2,674 of them, some with compact blue cores or globular clusters, offering a glimpse into the earliest stages of galactic evolution.
So, where does this leave us? Thanks to Euclid, our understanding of the galactic tuning fork is becoming sharper and more nuanced. We’re not just mapping galaxies—we’re tracing their life stories, from birth to merger, and the role black holes play in their transformation. But here’s the question we can’t ignore: if dwarf galaxies are the building blocks of giants like the Milky Way, what does that tell us about our own cosmic origins? And how will Euclid’s continued discoveries reshape our understanding of the universe?
As we await the next data releases, one thing is clear: Euclid is rewriting the rulebook on galactic evolution. What do you think? Are we on the brink of a cosmic revolution, or is there more to the story? Let’s discuss in the comments!
