Formation of First Galaxies: Birth of Stellar Structures

Approximately 13.5 billion years ago, just 300 million years after the Big Bang, the first galaxies began to form in the universe. These primitive galaxies were small, irregularly shaped aggregations of gas that collapsed under gravity to form compact stellar structures. Led by the gravitational influence of dark matter halos, hydrogen and helium gas clouds condensed and ignited the first generation of stars, creating the earliest galactic structures. These primordial galaxies were fundamentally different from modern galaxies—smaller, bluer, and with intense star formation rates—marking the transition from a dark, homogeneous universe to one with distinct, luminous structures.