About 4.5 billion years ago, a cataclysmic impact created the moon out of rubble from a barely formed Earth. Back then, the planet was a rather humdrum place, many geoscientists have assumed, with lava occasionally oozing across a global expanse of crust, and the formation of the planet’s more complex geological features still a long way off.

But according to a new model, the young moon was zipping around so closely to Earth at that time that it had a profoundly strange effect on our embryonic home.

The moon at that stage was up to 30 times closer to Earth than it is now. New calculations find that this proximity upset the equilibrium between Earth and moon’s orbital waltz. Ultimately,