In a surprising twist on our planet’s ancient history, scientists are now suggesting that Earth might once have had a ring system, similar to the rings we see around Saturn today. A new study presents compelling evidence that this ring formed around 466 million years ago, during the Ordovician period. It would have developed after a near-miss encounter with a massive asteroid.
And this might have changed Earth’s climate and geological history forever.
From Asteroids to Rings
Around 466 million years ago, during a period known as the Ordovician, Earth was pummeled by an unusually high number of meteorites. The evidence is scattered across the globe in the form of impact craters and layers of debris, most of which are curiously concentrated near the equator. This anomaly has long puzzled scientists.
In a recent paper published in Earth and Planetary Science Letters, a research team, led by Professor Andy Tomkins from Monash University, proposed an intriguing explanation: Earth may briefly have resembled Saturn. Earth could have had its own ring system.
The team used a combination of geological mapping and computer modeling to trace the origin of 21 asteroid impact craters from this period, all of which fell within 30 degrees of the equator. Given that 70 percent of Earth’s landmass at the time lay outside this region, the clustering of these craters defies statistical odds.
“Under normal circumstances, asteroids hitting Earth can hit at any latitude, at random, as we see in craters on the Moon, Mars and Mercury,” Tomkins wrote in a blog post.
According to the researchers, the most plausible explanation is that a large asteroid likely passed too close to Earth and broke apart, forming a temporary debris ring. Over millions of years, this material gradually fell to Earth, causing the meteorite impacts seen today in the geological record. Evidence for this comes from a dramatic rise in L-chondrite meteorites found in sedimentary layers around the globe during this time.
Planetary Dynamics
Rings around planets are not unique — Saturn, Uranus, and Neptune all have them. Even Mars might have had a ring in the past. Could Earth have been part of this planetary ring club too?
The idea that Earth could have had a ring system may sound outlandish at first, but it’s based on well-established principles of planetary dynamics. When a small celestial body, like an asteroid, comes too close to a larger body — inside what’s known as the Roche limit — it gets pulled apart by tidal forces.
Scientists believe this is what happened 466 million years ago. The asteroid, likely a fragment of a larger cosmic collision, disintegrated, and the debris formed a ring that orbited the planet. Over time, gravity caused pieces of the ring to drift toward Earth, creating the recorded spike in meteorite impacts. These impacts didn’t happen evenly across the globe but were concentrated near the equator, above which the ring itself was positioned. This would explain why we see such an unusual distribution of craters from this time period.
“So if Earth destroyed and captured a passing asteroid around 466 million years ago, it would explain the anomalous locations of the impact craters, the meteorite debris in sedimentary rocks, craters and tsunamis, and the meteorites’ relatively brief exposure to space radiation,” Tomkins wrote.
A Ring That Cooled the Planet?
While the idea of a ringed Earth is astonishing, what makes this discovery even more exciting is its potential connection to one of the planet’s coldest eras — the Hirnantian Ice Age. Occurring roughly 20 million years after the formation of this hypothesized ring, the Hirnantian period saw a dramatic drop in global temperatures. Could the ring have played a role?
The researchers speculate that the ring may have acted like a giant sunshade, blocking sunlight and causing a gradual cooling effect. This would have lowered temperatures, possibly triggering or contributing to the ice age.
“While we can’t say for certain that the ring caused the ice age, the timing and the evidence are intriguing,” said Professor Tomkins. “It’s a hypothesis that deserves further investigation.”
A New Frontier in Understanding Earth’s Past
This discovery could shift how we think about Earth’s interaction with the solar system. If rings can form around planets like Saturn, Jupiter, and even Mars — why not Earth? And if Earth did have a ring, how many times has this happened throughout its 4.5 billion-year history?
The team’s next step is to run detailed models of how such a ring might have affected Earth’s climate. By better understanding the formation and evolution of planetary rings, researchers hope to explore whether other ancient ring systems could have impacted Earth’s climate or even life itself.
While this study focuses on a period hundreds of millions of years ago, it raises broader questions about Earth’s dynamic relationship with space. Could other ring systems have existed at different points in our planet’s history? How have cosmic events shaped not just our geology but the evolution of life?
As the researchers continue to investigate, one thing is clear: the story of Earth’s past may be even more complex — and more cosmically connected — than we ever imagined.
This article originally appeared in September 2024 and was republished with new information.
