The researchers speculate that the ring could have cast a shadow on Earth, blocking sunlight and contributing to a significant global cooling event known as the "Hirnantian Icehouse."Earth may have had a ring system 466 million years ago
Normally, asteroids impact the Earth at random locations, so we see impact craters distributed evenly over the moon and Mars, for example. To investigate whether the distribution of Ordovician impact craters is non-random and closer to the equator, the researchers calculated the continental surface area capable of preserving craters from that time.posted by y2karl at 12:08 PM on September 19, 2024
They focused on stable, undisturbed cratons with rocks older than the mid Ordovician period, excluding areas buried under sediments or ice, eroded regions, and those affected by tectonic activity. Using a GIS approach (Geographic Information System), they identified geologically suitable regions across different continents.
Regions like Western Australia, Africa, the North American Craton, and small parts of Europe were considered well-suited for preserving such craters. Only 30% of the suitable land area was determined to have been close to the equator, yet all the impact craters from this period were found in this region.
The chances of this happening are like tossing a three-sided coin (if such a thing existed) and getting tails 21 times.
HighlightsEvidence suggesting that earth had a ring in the Ordovician
? Earth may have had a ring during the middle Ordovician, from ca. 466 Ma.
? Breakup of an asteroid passing within Earth's Roche limit likely formed the ring.
? Among several features preserved is a near-equatorial band of impact craters.
? Shading of Earth by the ring may have triggered a global icehouse period.
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