Earth and Moon hit 800 million years ago

A GIANT meteor shower bombarded Earth and the Moon 800 million years ago with more than 30 times the force of the asteroid strike that killed the dinosaurs, new research showed on Tuesday.

Japa nese scient ists exa mi ned i mages t a ken by t he Kag uya lu na r orbiter a nd fou nd t hat a n enor mous asteroid – at least 100k m in d ia meter – broke up a nd plunged into the Earth-Moon System, hav i ng a profou nd impact on life on our planet.

The probabilit y of an asteroid t hat size hitting Eart h is roughly once in 100 million years, and impact craters of meteor strikes created before 600 mil l ion yea rs ago have been erased by aeons of erosion a nd ot her geolog ic a l processes.

But there is virtually no erosion on the Moon, allowing the team to reconstruct the history of nearly 60 large craters.

Resea rcher s f rom Osa k a Universit y looked at t he age the large craters were formed by examining the densit y of smaller craters wit hin t heir ejecta range – where chunks of rocks would have la nded after the main impact.

They used sca ling laws and collision probabilities to ca lculate that the mass of meteors to st r i ke Ea r t h a nd t he Moon was 40-50 million bill ion ton nes – t hat ’s 30- 60 times greater than the Chicxulub impact event.

This strike, approx imately 65 million years ago in what i s moder n-day Mex ic o, i s thought to have led to a mass e x t i nc t i on of more t h a n t h r e e - qua r t er s of l i f e on Ea r t h, i nclud i ng non-av ia n dinosaurs.

The tea m sa id t he shower 800 million years ago struck Ea r t h just before t he Cr yogenia n period, which saw a planet-wide ice age bet ween 720-635 million years ago.

Wr it i ng i n t he j ou r n a l Nat u r e Com mu n ic at ion s , t hey said t he k nock-on effect to l i fe on Ea r t h must have been profound.

“Our new finding suggests t hat t he f lu x of ex t rater rest r ia l element s mig ht have i nf luenced marine biogeochem ic a l c ycles . . . s evere pert urbations to Earth’s climate system, and the emergence of animals,” t hey said.

The Kag uya mission was launched in 2007 and studied Eart h’s satel l ite in t hen-unprecedented detail, including the dark side of the Moon and its magnetic f ield.

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