Ordovician. This term, unknown to the general public, comes from the name of a Welsh tribe, and describes a period in Earth's history between 485 and 444 million years ago. It is characterised by the coincidence of major glaciations and a dramatic increase in asteroid impacts.
Massive collisions would have created a ring of debris that would have lasted tens of millions of years, giving Earth its Saturn-like appearance. This ring may have led to global cooling, contributing to the coldest period on Earth in the past 500 million years.
A large asteroid has changed the Earth's climate.
This is the hypothesis formulated in a new study published in the journal Earth and Planetary Sciences Letters It is led by Andy Tomkins, a professor of planetary science at Monash University in Australia. His team of researchers analyzed 21 crater sites around the world, all of which were created by debris from a large asteroid between 488 and 443 million years ago, which corresponds to the Ordovician period.
Using computer models of how tectonic plates moved in the past, they were able to map out where the craters were when they formed more than 400 million years ago. The team found that all of the craters formed on continents that were floating 30 degrees from the equator, suggesting they were created by debris falling from a single large asteroid that broke apart after colliding with Earth.
All holes are connected.
“Under normal circumstances, asteroids that strike Earth can strike at any latitude, and randomly, as we see with craters on the Moon, Mars, and Mercury,” Tomkins wrote in a paper published in the journal. Conversation“It is therefore extremely unlikely that the 21st crater from this period formed near the equator if they were not related to each other.”
These researchers also claim that this series of craters corresponds to a ring of debris orbiting the Earth. A ring similar to those that generally form above the equator of planets, such as those surrounding Saturn, Jupiter, Uranus and Neptune.
orbital debris ring
In that same study, we learned that the asteroid at the origin of the ring was about 12.5 kilometers wide. Once it broke apart as it approached Earth, its fragments “wandered” before settling into a ring of debris orbiting Earth’s equator, Tompkins said.
“Over millions of years, material from this episode gradually fell to Earth, resulting in the peak of meteorite impacts observed in the geological record,” Tompkins continued in a university press release. “We also see that sedimentary rock layers from this period contain unusual amounts of meteorite debris.”
There are still grey areas…
If Earth had a Saturn-like ring around its equator, that ring would have a major impact on our planet’s climate, according to the new study. Because Earth’s axis is tilted relative to its orbit around the sun, the ring could cast shadows on parts of our planet’s surface, potentially causing global cooling.
Although they admit that all of this is still unclear, the researchers hypothesize that such an event could have contributed to the dramatic cooling of our planet 465 million years ago: “We don’t know what the ring would have looked like from Earth, nor how much light it would have removed, nor how much debris would have had to be present in the ring to lower the temperature on Earth. New world.
