466 million years ago, Earth may have had a Saturn-like ring

Researchers have found clear indications that Earth may have had a ring system hundreds of million years ago. The recent discovery challenges the understanding of Earth’s ancient history.

They made the claim after studying more than a dozen asteroid impact craters on Earth. Researchers studied 21 such craters, which are almost 500 million years ago.

All these craters are located within 30 degrees of the equator, despite over 70 per cent of Earth’s continental crust being outside this region, an anomaly that conventional theories cannot explain, claimed researchers.

Meteorite impacts observed in geological record

This localised impact pattern was produced after a large asteroid had a close encounter with Earth . As the asteroid passed within Earth’s Roche limit, it broke apart due to tidal forces, forming a debris ring around the planet—similar to the rings seen around Saturn and other gas giants today, according to researchers .

“Over millions of years, material from this ring gradually fell to Earth, creating the spike in meteorite impacts observed in the geological record,” said lead study author Professor Andy Tomkins, from Monash University’s School of Earth, Atmosphere and Environment.

“We also see that layers in sedimentary rocks from this period contain extraordinary amounts of meteorite debris. What makes this finding even more intriguing is the potential climate implications of such a ring system,” he said.

Ring could have cast a shadow on Earth

Published in the journal Earth and Planetary Science Letters, the study suggests that the ring could have cast a shadow on Earth, blocking sunlight and contributing to a significant global cooling event known as the Hirnantian Icehouse.

This period, which occurred near the end of the Ordovician, is recognised as one of the coldest in the last 500 million years of Earth’s history.

Tomkins claimed that 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.

Implications of this discovery extend beyond geology

Normally, asteroids impact the Earth at random locations, so we see impact craters distributed evenly over the Moon and Mars, for example. To investigate whether the distribution of Ordovician impact craters is non-random and closer to the equator, the researchers calculated the continental surface area capable of preserving craters from that time, according to researchers from Monash University .

Researchers focused on stable, undisturbed cratons with rocks older than the mid Ordovician period, excluding areas buried under sediments or ice, eroded regions, and those affected by tectonic activity. Using a GIS approach (Geographic Information System), they identified geologically suitable regions across different continents. Regions like Western Australia, Africa, the North American Craton, and small parts of Europe were considered well-suited for preserving such craters.

Researchers maintained that the implications of this discovery extend beyond geology, prompting scientists to reconsider the broader impact of celestial events on Earth’s evolutionary history. It also raises new questions about the potential for other ancient ring systems that could have influenced the development of life on Earth.