Researchers have come across some evidence suggesting Earth had a ring system around 466 million years ago, which may have been a contributor to the global cooling event known as the Hirnantian Icehouse. The hypothesis comes from plate tectonic reconstructions for the Ordovician period, a period of unusually intense meteorite bombardment.

There has been plenty of research and data collected concerning Saturn's rings, including a stunning image of the spectacular rings by NASA's Webb Space Telescope. Ring formations around smaller celestial bodies, however, are still not well understood, as noted by another recent study. That study remarked rings around minor planets have only been recently discovered, and only a small number of such systems are currently known. So, the hypothesis that Earth may have had its own ring system at one point in history is surprising.

The research team from Monash University noted the positions of 21 asteroid impact craters. All 21 are located within 30 degrees of the equator, despite over 70% of Earth's continental crust being outside this region, an anomaly that conventional wisdom cannot explain, according to the researchers.

The team believes this localized impact pattern was created after a large asteroid had a close encounter with Earth. As the asteroid passed within Earth's Roche limit, it broke apart because of tidal forces. This formed a debris ring around the planet, similar to the rings around Saturn.

"Over millions of years, material from this ring gradually fell to Earth, creating the spike in meteorite impacts observed in the geological record," remarked lead study author Professor Andy Tomkins, from Monash University's School of Earth, Atmosphere and Environment. "We also see that layers in sedimentary rocks from this period contain extraordinary amounts of meteorite debris."

Tomkins added that what makes the find even more intriguing is the potential climate implications a ring system would have brought with it. The researchers suggest the ring could have cast a shadow on Earth, blocking sunlight and helping to cause a significant global cooling event known as the Hirnantian Icehouse. Tomkins says the idea of a ring system influencing global temperatures would add a "new layer of complexity to our understanding of how extra-terrestrial events may have shaped Earth's climate."

The new theory of Earth having a ring system at one point in its past has implications beyond just geology and climate. It also brings up new questions about how a ring system may have influenced the development of life on Earth, and if the planet could have had rings at other points in its history. The team says the finding "opens a new frontier in the study of Earth's past."