Did the Earth have rings 466 million years ago?

Several planets in our solar system have rings. Even some asteroids have rings. But why not Earth? According to a new study, Earth once had its own rings, some 466 million years ago.

Did the Earth have rings 466 million years ago?
Ring systems are common in our solar system. Saturn, Jupiter, Uranus, Neptune, and even some dwarf planets and asteroids have rings. Earth, unfortunately, does not. But it may have had them in the past.
At least that's what the investigators said. Monash Universityin Australia, on September 16, 2024. Your study of asteroid impact craters from 466 million years ago - during the Ordovician period medium - shows that Earth may have had its own ring system.
The researchers, led by Andy Tomkins from the School of Earth, Atmosphere and Environment at Monash University, published their findings in the journal Earth And Planetary Science Letters on September 12, 2024.

What would Earth look like with rings?
Since both larger planets and smaller bodies, such as asteroids, can have rings, why not Earth? Our planet has never had rings adorning its skies. Or has it?
Researchers hypothesize that a large asteroid passed close to Earth about 466 million years ago. It passed close enough to be within the Roche limit. This is the minimum distance at which a smaller body can approach a larger primary body without causing the tidal forces overcome the internal gravity that holds the satellite together.
In other words, if the smaller body gets too close, it will be torn apart. In this case, Earth's gravity tore the asteroid apart. The resulting debris began to orbit Earth, forming a ring or rings.

Barringer Crater, also known as Meteor Crater, is located near Winslow, Arizona, United States.

Traces of two asteroid impacts
How did researchers determine that an asteroid formed a ring, and when? They examined the sites of 21 known asteroid impacts dating back to the Ordovician Period, 466 million years ago. And they noticed something unusual.
All of the craters were located within 30 degrees of the equator. This seemed odd, since more than 70 percent of Earth's continental crust—which forms almost all of the Earth's surface—lies outside this region.

Why were the craters confined to this region? The research team postulated that the craters formed from debris that gradually fell from the rings to Earth over time.

Over millions of years, material from this ring gradually fell to Earth, creating the peak of meteorite impacts observed in the geological record. We also found that sedimentary rock layers from this period contain extraordinary amounts of meteorite debris.

Disse Tomkins.
But were these impacts really non-random?
To answer this question, the researchers calculated the area of ​​the continental surface capable of preserving craters from that time. The researchers analyzed cratons—large parts of the continental crust that have remained stable—with rocks older than the middle Ordovician period.
The researchers ruled out areas buried under sediment or ice, eroded regions and areas affected by tectonic activity. They found suitable regions on several continents, including Western Australia, Africa, the North American Craton and small parts of Europe. These areas should have preserved craters, if they existed.
But all the impact craters were in the 30% of the cratons that were found near the equator. According to researchers, this fact shows that the distribution of craters was not random.
They compared it to flipping a three-sided coin and having it land on heads 21 times.

Effects on climate
The ring system may also have affected Earth's climate.
The rings may have had a cooling effect, which would also explain another aspect of the Late Ordovician period. It was certainly cold on Earth!
In fact, It was one of the coldest times in the last 500 million years. The ring system may have cast a shadow over Earth, partially obscuring sunlight. Researchers say this may have contributed to a period of global cooling called Hirnantian. The Hirnantian was the final phase of the Ordovician Period.
So, for now, the study indicates that the Earth may have had rings around 466 million years ago. As to how they disappeared, there are still no clues.