Earth had a ring system 466 million years ago: Study
A recent study suggests that Earth, in all likelihood, had a ring system around it approximately 466 million years ago. This period, known as the Ordovician impact spike, was marked by an unusually intense bombardment of meteorites. The theory, published in Earth and Planetary Science Letters, is based on the locations of 21 asteroid impact craters and plate tectonic reconstructions from the Ordovician period.
Researchers suggest Earth's ring similar to Saturn's
The researchers' theory is based on the locations of 21 asteroid impact craters, all of which are situated within 30 degrees of the equator. This distribution is considered unusual as over 70% of Earth's continental crust lies outside this region. The scientists propose that a large asteroid once flew extremely close to Earth, breaking apart due to tidal forces within Earth's Roche limit and possibly forming a debris ring around the planet.
Asteroid debris may have created Earth's ancient ring
The asteroid debris, according to the researchers, rained down onto Earth over numerous tens of millions of years. This process likely resulted in the creation of the observed pattern of sediments, craters, and tsunamis. Lead study author Professor Andy Tomkins from Monash University's School of Earth, Atmosphere, and Environment explained that, over millions of years, material from the ring gradually fell to Earth, which led to the spike in meteorite impacts observed in the geological record.
Earth's ancient ring may have influenced global climate
The ancient ring might have also affected Earth's climate by casting a shadow and blocking sunlight, leading to a cooling of the environment. This significant global cooling event is known as the "Hirnantian Icehouse." Professor Tomkins further noted that sedimentary rock layers from this period contain extraordinary amounts of meteorite debris. He noted that the possibility of a ring system influencing global temperatures introduces a new complexity to our understanding of how extraterrestrial events may have impacted Earth's climate.
Earth's ancient ring aligned with continental drift
During the Ordovician period, the continents were positioned differently due to continental drift. North America, Europe, and Australia were near the equator, while Africa and South America were at higher southern latitudes. The ring would have encircled the equator, and due to Earth's tilted axis relative to its orbit around the Sun, it would have cast shadows on certain parts of Earth's surface. This period is one of the coldest witnessed in the last 500 million years of Earth's history.
Future research to explore possibility of multiple rings
This discovery has led astronomers to ponder whether Earth could have had these rings more than once in its history. The next phase of research will involve creating mathematical models to understand how asteroids break up and disperse, and how the resulting ring evolves over time. This will set the stage for climate modeling that explores how much cooling could be imposed by such a ring.
