Proposed rings of Earth that existed 446 million years ago
The rings of Earth are a proposed set of planetary rings that may have at one point been present around Earth during the Ordovician period. These rings may have formed during the Ordovician impact spike approximately 466 million years ago.[1][2][3] They were first formally proposed by a team of scientists working with the Monash University in September 2024, and have been a subject of interest for several years prior to the study.
The Ordovician Period was the geologic period and system that the Earth was in when the rings are believed to have formed. The Ordovician spanned from 485.4 million years ago to 443.8 million years ago. During this period, an event known as the Ordovician meteor event occurred, when a high level of L chondrite meteorites hit Earth. The meteorites may have been caused by a large parent body that was 93 miles (150 km) in diamater.[4]
History
Formation
The parent body that produced the L chondrite meteorites is believed to have passed Earth's Roche limit, leading to the body being torn apart and its debris being scattered around, which eventually led to the formation of a debris ring.[5][6]
Post-formation
The rings are believed to have been present approximately 466 million years ago.[1][7][8] The Hirnantian glaciation may be a direct result of the rings shielding light from reaching the Earth,[9] and the rings may have existed for up to 40 million years.[9]
Studies
2024 study
The ring was first formally proposed after 21 impact craters from the meteor event were found to be located along a straight band around the Earth's equator.[10][11] Andrew G. Tomkins,[9] Erin L. Martin[9] and Peter A. Cawood,[9] working with Monash University, released a study in September 2024 that gave evidence on the existence of the rings.
The study noted that all 21 craters produced as a result of the meteor event fell within an equatorial band range of ≤30°, despite the fact that ~70% of the Earth has a crust suitable for the preservation of craters. The study also noted that the chances of all 21 craters falling within the 30° range was one in 25 million, and would be highly unlikely unless the craters were caused by a dissolved ring system.[9]