The Moon is born
A Mars-sized planet strikes Earth
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The leading explanation is that a protoplanet, often called Theia, struck the young Earth at an angle. The collision melted both bodies and threw a disc of vaporised mantle material into orbit, where it coalesced into the Moon in perhaps only decades. The Moon stabilises the tilt of Earth's axis over long timescales, giving us a remarkably steady climate and predictable seasons — one of several accidents that made complex life possible.
For children
A planet as big as Mars smashed straight into Earth. Molten rock sprayed into space and formed a ring around us — and that ring clumped together into the Moon. Without that crash, Earth would have a completely different climate.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org