Earth likely had a ring around it 466 million years ago. It was created by...

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Earth may have had a ring system that came into existence around 466 million years ago, a new study has suggested. This was the period when our planet was bombarded with unusually intense meteorites known as the Ordovician impact spike. 

The theory has been published in Earth and Planetary Science Letters. It is based on the positions of 21 asteroid impact craters and plate tectonic reconstructions for the Ordovician period.

Researchers cite the place where the craters exist on Earth to suggest that the planet once likely had a ring, just like Saturn. All of the craters studied are located within 30 degrees of the equator. However, this is considered an anomaly since more than 70 per cent of Earth's continental crust is outside this region.

They believe the reason for this localised impact pattern was a large asteroid which once might have flown by extremely close to Earth. When this happened, it passed within Earth's Roche limit, breaking apart due to tidal forces. This, they say, might have formed a debris ring around the planet, similar to Saturn's rings and those of other gas giants. 

When these meteorites fell on Earth, they likely created the craters now seen in the region.

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

Also Read: Collision of asteroids created cosmic dust and sparked life on Earth: Study

"We also see that layers in sedimentary rocks from this period contain extraordinary amounts of meteorite debris."

This ring might have also impacted our planet's climate which would have cast a shadow, and blocked the sunlight, thus cooling down the environment. This significant global cooling event was known as the "Hirnantian Icehouse."

"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," Professor Tomkins said.

Having occurred near the end of the Ordovician, this period is one of the coldest witnessed in the last 500 million years of Earth's history.

The latest discovery also leads astronomers to think whether Earth could have these rings more than once in its lifetime.