Meteorite discovery upends our understanding of life on Earth
There's evidence that like Saturn, Earth once had a ring around it, and its shadow likely altered the way life developed.
Analysis of a strange pattern left on the Earth’s surface by a meteor shower has upended our understanding of how the planet appeared 466 million years ago, and how life developed.
A group of Aussie scientists believe a formation of craters around the equator suggests our planet may have once been surrounded by rings, similar to what we now see around Saturn.
The research published in the journal Earth and Planetary Science Letters examined 21 impact sites across Australia, China, India, North America, Europe and Russia from the Ordovician period. What they expected to see were random craters on the surface like we see on the Moon. But instead they found all of the craters were clustered within 30 degrees of the equator.
Because over 70 per cent of Earth’s continental crust is outside this region, there was little possibility they fell into such a pattern by chance. They calculated the odds of it occurring would be like flipping a three-sided coin and getting heads 21 times in a row.
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Why does the meteor pattern suggest there was a ring around Earth?
The team of Monash and Melbourne University geologists believe a likely reason for the pattern is that it was produced by a large asteroid which had a close encounter with Earth. As the object was broken apart by tidal forces as it passed within Earth’s Roche limit, they theorise it formed a ring of debris. Over time the material in the ring would have fallen to the ground and the larger pieces would have formed impact craters.
“Over millions of years, material from this ring gradually fell to Earth, creating the spike in meteorite impacts observed in the geological record,” lead author Professor Andy Tomkins said.
How did the ring around Earth impact life?
Despite the ring being high above the Earth, it’s believed to have had a big impact on the surface below because it could have a large shadow. The cooling effect could have been so immense, it may have contributed to a cooling event at the end of the Ordovician period known as the Hirnantian Icehouse — one of the planet’s coldest ever periods.
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This intense cold-snap would likely have impacted the development and distribution of life.
“The idea that a ring system could have influenced global temperatures adds a new layer of complexity to our understanding of how extra-terrestrial events may have shaped Earth’s climate,” Tomkins added.
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