4.5 Billion Years in 1 Hour

The first eon, the Hadean, named after the Greek god of the underworld, sees an atmosphere mostly composed of CO2 and a surface of lava. Surprisingly, minerals like zircons suggest the early presence of water, despite the extreme conditions. The young solar system experiences a heavy asteroid bombardment for hundreds of millions of years.

Around this time, life begins to appear. The planet cools, leading to millions of years of rain that form the oceans, covering the young Earth with water. Hydrothermal vents are theorized as potential cradles for primitive life.

Entering the Paleoarchean, most of Earth remains underwater, with the first supercontinents forming beneath the surface. The young Earth spins faster, resulting in shorter days. Evidence of early life such as stromatolites emerges, and photosynthesis likely begins, with microbes starting to harness solar energy.

The Mesoarchean marks the era of continental formation as tectonic plates begin to move and clash, forming the basis for today's continents. Oceans are very hot, over 40°C, and microbes thrive in a greenhouse gas-rich, oxygen-free atmosphere. The Neoarchean sees increased tectonic activity, leading to greater chemical mixing from within the Earth, which supports further diversification of life, including prokaryotes like bacteria.

The Siderian period brings the Great Oxidation Event, where oxygen produced by cyanobacteria accumulates in the atmosphere, enabling more complex life. This new oxygen reacts with methane, cooling the planet rapidly and initiating a period of multiple ice ages lasting millions of years.

Volcanic activity eventually warms Earth, leading to a slow unfreezing. Melting ice flushes toxic elements into the oceans, but life continues to evolve. In the Orosirian, a massive asteroid impact creates Earth's largest verified impact structure, and early continents like Ur, Nena, and Atlantica form new mountain ranges.

The supercontinent Columbia forms in the Statherian. Around this time, naturally occurring nuclear reactors activate from scattered uranium deposits. The Callimian period sees the emergence of the first Eukaryotic cells, a pivotal moment in the history of life, though life remains microscopic. Earth's crust thickens, continents grow, and fungi-like organisms begin to appear.

In the Ectasian, Earth's inner core begins to solidify into an iron crystal. The Stenian period is notable for the potential invention of sexual reproduction by the algae Bangiomorpha pubescens, a significant reproductive improvement.

The Tonian period sees Earth as a landscape of rocks and oceans, with life still invisible to the naked eye. Unicellular predators emerge, marking the end of bacterial dominance and initiating an evolutionary arms race among microbes, leading to greater diversity and defenses like tiny armor.

The Cryogenian period brings another global freeze, a 'Snowball Earth' event. Later, the supercontinent Gondwana forms. A rapid increase in complexity occurs with the widespread appearance of multicellular organisms. The Cambrian explosion, 539 million years ago, showcases a burst of life's variety, with ancestors of most major animal groups appearing, and plants beginning to colonize land. This period is followed by a significant mass extinction event.

Plants spread across the planet, creating soil and changing the atmosphere by consuming CO2. Flora and fauna adapt to terrestrial life; trees and forests emerge, and the first vertebrates venture onto land. The Carboniferous period, 359 million years ago, sees peak forest and marshland growth, which will later become the coal reserves used by humanity.

The supercontinent Pangea forms in the Permian. This period culminates in the largest mass extinction in history, killing most species, likely due to massive volcanic activity. The Triassic period, 252 million years ago, begins the Age of Reptiles, dominated by dinosaurs, with ancestors of birds also emerging. Life thrives, making Earth increasingly familiar.

An asteroid impact catastrophically ends the reign of the dinosaurs and most other species. In the Paleogene, 66 million years ago, continents resemble their modern forms, and mammals take over as the dominant life forms. Human history, in the grand scheme of Earth's timeline, is incredibly brief and recent.

Earth forms 4.5 billion years ago as a hell of lava. A collision with a Mars-sized object called Theia forms the Moon, which initially appears huge in the night sky and slowly recedes over millions of years.