Episode 1 of The Story of Life on Earth goes back before there was any life to tell a story about. It starts 13.8 billion years ago with the Big Bang and follows the chain of events that built the stars, the sun and the planets, ending on a young Earth that was finally ready for chemistry to begin.
The episode moves from an empty universe to the first hydrogen and helium, the first stars switching on after a long dark age, and the slow gathering of galaxies, one of them the Milky Way. Inside it, a collapsing cloud of gas and dust became the sun, and the debris left spinning around it clumped into four rocky inner planets.
Earth took its shape through repeated collisions. The largest came around 4.5 billion years ago, when a Mars-sized body called Theia struck the young planet. The debris from that impact gathered into the Moon, which went on to steady the tilt of Earth’s axis and, with it, the planet’s climate. Tiny zircon crystals from the Jack Hills of Western Australia, dated to about 4.4 billion years ago, suggest that Earth had cooled enough for surface water much sooner than scientists once thought.
The series follows the same path as Martin Jenkins’s 2019 book Life: The First Four Billion Years, illustrated by Grahame Baker-Smith, which traces Earth’s story from the Big Bang through the fossil record and the age of dinosaurs to the first humans.
Watch Episode 1 on YouTube, read the companion piece on Medium, continue to Episode 2, The First Spark, or jump ahead to the dinosaur episode. The full series is on the YouTube Series page.