Hadean eon: hellish first 600 million years of Earth
From 4.6 to 4.0 billion years ago Earth was a magma ocean with impacts, yet oceans formed by 4.4 billion years ago.
Magma ocean and Moon birth
The Hadean lasted from about 4.6 to 4.0 billion years ago, roughly 600 million years of molten hell. Earth grew by violent collisions, and about 4.51 billion years ago a Mars-sized body struck it, melting the surface and blasting the Moon into orbit.
The surface stayed near 1200 degrees for millions of years, with a glowing magma ocean hundreds of kilometers deep. Heavy iron sank to make the core, lighter rock floated as crust, and volcanoes pumped steam, carbon dioxide and nitrogen into a thick airless sky.
Bombardment, oceans, still no life
The Moon was already in the sky, much closer, raising tides hundreds of meters high, while asteroids kept striking during the Late Heavy Bombardment around 4.1 to 3.8 billion years ago. Craters melted young crust again and again, yet between strikes the surface cooled enough for rain.
Zircon crystals from Jack Hills in Australia, dated to 4.4 billion years ago, prove liquid water and cool oceans already existed. That water likely came from volcanic steam and icy asteroids, but there was no oxygen and no life yet — only chemistry preparing for the Archean.
- Hadean: 4.6 to 4.0 billion years ago
- Length: about 600 million years
- Moon impact: about 4.51 billion years ago
- First oceans: by 4.4 billion years, zircons
- Life: none yet, no oxygen