New research indicates that Earth may have had a ring system about 466 million years ago. This ring structure might have emerged during an era of heightened meteorite activity known as the Ordovician impact spike.
The research, featured in Earth and Planetary Science Letters, analyzes the geographic distribution of 21 asteroid impact craters on Earth using plate tectonic reconstructions from the Ordovician period.
Scientists observed that all examined craters are situated within 30 degrees of the equator. This concentrated impact area, uncommon since more than 70% of Earth's continental crust exists beyond this zone, suggests the existence of an ancient debris ring around Earth.
Researchers suggest that a large asteroid likely passed extremely close to Earth, crossing its Roche limit. Tidal forces would have broken the asteroid into fragments, potentially creating a debris ring around Earth, much like the rings surrounding gas giants such as Saturn.
Over millions of years, pieces from this debris ring likely descended to Earth, leading to an increase in meteorite impacts. This trend is reflected in geological records from that era.
The research identified unusually high concentrations of meteorite fragments in sedimentary rock layers from this period, reinforcing the theory of an Earth ring system gradually releasing its material over time.
The ancient ring may have cast a shadow over Earth, reducing sunlight and helping to cool the planet. This timeframe aligns with the "Hirnantian Icehouse," one of Earth’s coldest periods in the past 500 million years.
Scientists are exploring the possibility that Earth may have had multiple ring systems throughout its geological past, offering new insights into how extraterrestrial impacts may have influenced Earth's climate.