A galaxy is a vast ensemble of billions of stars, gas, dust, and dark matter. The mass of a typical galaxy far exceeds a hundred million solar masses. These colossal structures are the fundamental building blocks of the observable Universe and come in various forms, from elegant spirals to massive ellipticals, including irregular galaxies.
Galaxies do not evolve in isolation: they interact with their neighbors. These gravitational interactions can distort their spiral arms, trigger bursts of star formation, or even lead to spectacular mergers. These processes play an essential role in the evolution of galaxies and in the diversity of their morphologies.
Galaxies often group together in clusters containing hundreds or even thousands of members bound by gravity. These clusters are some of the largest coherent structures in the Universe. Their study helps us better understand the distribution of matter, both visible and invisible, as well as the large-scale dynamics of the cosmos.
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The Great Attractor: The Celestial Fountain Pulling Us into the Abyss 
The 5 Strangest Objects in Our Galaxy: From Zombie Stars to Diamond Planets 
Why Is It So Hard to See the Milky Way? 
What Is a Galaxy? Journey to the Land of Billions of Stars 
Galaxies from the Depths: Light from the Primordial Universe 
Journey to the Heart of the Milky Way: Mysteries and Wonders 
JWST and Protogalaxies: Exploring the First Cosmic Structures 
Collision and Cannibalism: How Large Galaxies Absorb Smaller Ones 
Beyond Our Senses! 
Future Collision of Our Galaxy with the Sagittarius Galaxy 
Differences between the Milky Way and the Andromeda Galaxy 
Why are Galaxies, Unlike Stars, So Close to Each Other? 
Galaxies of the Local Group 
The hidden galaxy, one of Euclid's first images 
The Virgo Cluster spans approximately three Full Moons 
Where did the dark matter in our Galaxy go? 
Galaxy Mergers: From Encounter to Coalescence 
Gravitational Lenses: When Spacetime Bends Light 
Cartwheel Galaxy: A Wheel of Fire in the Universe 
From Dust to Stars: The Composition of Galaxies 
Galaxy Merger NGC 6745: A Traversal of One by the Other 
The mystery of gamma bursts 
The Cigar Explosion 
Extreme Shock Waves in the Universe: Impact on the Evolution of Cosmic Structures 
Gould's belt, a stellar fireworks display 
Zoom on Our Galaxy: Journey to the Center of the Milky Way 
One Galaxy, Two Hearts: The Mystery of Andromeda's Double Nucleus 
The most beautiful galaxy clusters 
Tinker Bell's Gravitational Flight: A Merger of Three Galaxies 
Coma or Berenice’s Hair: The Cosmic Colossus 
When Dark Matter Reveals Itself 
El Gordo galaxy cluster 
Einstein ring and cross 
How to measure distances in the Universe? 
The Cigar Galaxy: A Smoke of Stars in the Night 
The Hubble Sequence: The Secret Code of Galactic Shapes 
Dance of the Stars: The Arms of the Milky Way 
The most beautiful galaxies 
Ancient Galaxies and Cosmic Evolution: A Deep Look Back in Time 
Quasars: Beacons of the Distant Cosmos 
Sagittarius A black hole at the center of our Galaxy 
MOND Theory and Dark Matter: Why MOND Fails in Cluster Collisions 
Central area of the Milky Way 
Laniakea, our supercluster of galaxies 
The Antennae Galaxies: An Ongoing Cosmic Collision 
NGC 1275: A Turbulent Galaxy in the Perseus Cluster 
NGC 1672: A Barred Spiral Galaxy in Full Activity