A new study has revealed that Earth may have had a ring system that came into existence around 466 million years ago. This was the time when our planet was subjected to an unusually intense meteorite bombardment known as the Ordovician impact spike.
The theory, published in Earth and Planetary Science Letters, is based on the position of 21 asteroid impact craters and plate tectonic reconstructions for the Ordovician period.
Researchers have cited the location of craters on Earth to suggest that the planet once had a ring like Saturn's. All of the craters studied are located within 30 degrees of the equator. However, this is considered an anomaly because more than 70 percent of Earth's continental crust lies outside this region.
They believe this localized impact pattern was caused by a large asteroid that once passed extremely close to Earth. When it did, it passed within Earth's Roche limit, and broke up due to tidal forces. They say this would have created a ring of debris around the planet, similar to the rings of Saturn and the other gas giants.
When these meteorites fell to Earth, they probably created the craters visible in this region today.
“Over millions of years, material from this ring slowly fell to Earth, leading to an increase in the number of meteorite impacts seen in the geological record,” said lead study author Professor Andy Tomkins, from Monash University's School of Earth, Atmosphere and Environment.
“We also observed that meteorite debris is present in extraordinary quantities in sedimentary rock layers from this period.”
This ring would have also affected our planet's climate, casting shadows and blocking sunlight, thus cooling the environment. This significant global cooling event is known as the “Hirnantian Icehouse.”
“The idea that a ring system could influence global temperatures adds a new layer of complexity to our understanding of how extraterrestrial events may have shaped the Earth's climate,” Professor Tomkins said.
Occurring near the end of the Ordovician Period, this period is one of the coldest in the last 500 million years of Earth's history.
The latest discovery has led astronomers to wonder if these rings could form more than once during Earth's lifetime.
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