About 13.8 billion years ago, the universe came into being in an event known as the Big Bang. It was not an explosion into empty space; rather, space and time themselves began to expand. In the first fractions of a second, the universe expanded at extraordinary speed in a phase called cosmic inflation. As it cooled, the fundamental forces of nature emerged, and particles of matter formed from pure energy.
Within the first few minutes, the simplest atomic nuclei — mainly hydrogen and helium, with traces of lithium — were created. For hundreds of millions of years, the universe remained dark, filled with vast clouds of gas slowly gathering under gravity. Eventually, these clouds condensed into the first stars, whose light pierced the cosmic darkness.
Inside these stars, nuclear fusion forged heavier elements such as carbon, oxygen, silicon, and iron — the essential ingredients for planets and life. When massive stars reached the end of their lives, they exploded as supernovae, scattering these newly formed elements across space. From the ashes of dying stars, new generations of stars and planetary systems were born.
Around 4.6 billion years ago, in one spiral arm of the Milky Way galaxy, a giant cloud of gas and cosmic dust began to collapse under its own gravity. Most of its material gathered at the center, forming the Sun. Around the young Sun, the remaining matter flattened into a rotating disc. Tiny particles collided, merged, and gradually built larger bodies over millions of years.
From this swirling disc emerged the planets, moons, asteroids, and comets of our solar system. The third planet from the Sun — a small rocky world with liquid water and a protective atmosphere — became Earth.
On this planet, forged from stardust and shaped by billions of years of cosmic evolution, life would eventually appear. And from that life, beings would arise capable of looking back into the universe and wondering how it all began
Back to the Story of Humankind