Rings are conventionally believed to be endemic to the outer planets of our solar system, but new research published in journal ScienceDirect last November suggests that the Earth too harbored a solitary ring hundreds of millions of years ago.
Within the solar system, rings are currently present around Jupiter, Uranus, Neptune, and most conspicuously, Saturn.
Indeed these rings are perhaps these planets’ most charismatic trait, with Jonah Royzen ’25 characterizing Saturn’s rings as both “very cool” and “interesting.”
The paper, authored by Andrew G. Tomkins, Erin L. Marti, and Peter A. Cawood suggests that a conspicuous spike in meteor impacts during the Ordovician period is best explained by a ring of debris once circling the planet.
The Ordovocian, which lasted from roughly 485 to 445 million years ago, predates the appearance of dinosaurs by over 200 million years ago and saw the first colonization of land by plants.
The Ordovocian also enjoys the title of being the period in Earth’s history where it was pummeled by the most meteors. For several dozen million years, there was a heavy influx of meteorite activity– estimated at a frequency of 100 times what is seen today–in what is known as the Ordivican meteor event.
These forms of meteors are specifically known as L chondrites, and are the second most common form of meteorite.
Traditionally, the Ordovician meteor event has been attributed to the catastrophic breakup of the L chondrite parent body within the asteroid belt, with the resulting debris then dispersing across the inner solar system, with some of these impacting the Earth.
Curiously, the meteor impacts associated with the Ordovocian meteor event–all 21 of them– occur within 30 degrees of the equator. This is despite the fact roughly 70 percent of exposed rock feasibly capable of preserving these impacts occurs outside of this interval.
If the meteor event had truly originated from the asteroid belt, one would expect there to be a random distribution of asteroids throughout the Earth.
Indeed, the authors of the 2024 paper calculate that the probability of the distribution of the 21 recorded impacts being the legitimate result of a random distribution to be one in 25 million.
Thus, the far more likely explanation is that these meteors were not impacting the planet at random, and that rather there was some other mechanism influencing where they impacted.
The authors propose that this mechanism may have been a ring system surrounding the planet, as any debris ejected from the ring would fall only a relatively short distance to Earth, thus resulting in the narrow “band” of impacts observed.
Riordan Science Instructor and Director of Professional Development Michael O’Brien affirmed the theory to be “feasible” and that in the event of an asteroid breakup, “the Earth’s gravitational pull may pull some [debris] into a ring while others pass by.”
This is of course, still somewhat speculative, but the authors conclude this is the most likely and parsimonious explanation of these curious circumstances.
And while this ring may not have been as dramatic as those of Saturn, the idea of a ringed primordial Earth offers a fascinating glimpse into the planet’s cryptic ancient history.
