Ever since the invention of the telescope, humans have looked to the planet Saturn in awe of its magnificent system of rings. Passing probes later discovered rings around the other gas giants: Jupiter, Uranus and Neptune. Ten years ago, a wispy ring was discovered around Chariklo , a planetoid some 200 kms in diameter, orbiting the sun beyond Saturn.
Where there’s one, there may be others. Now researchers at Monash University in Melbourne, Australia, have added Earth to the list of planets with rings. Don’t look up, though: This planet’s ring system, if it existed, formed more than 400 million years ago, long before humans or even dinosaurs roamed the Earth.
And it broke up a few tens of millions of years later, with pieces of it crashing to Earth as meteorites — which is how scientists deduced it was ever there. The paper, “ Evidence Suggesting That Earth Had a Ring in the Ordovician,” was just published in the journal Earth and Planetary Science Letters. The researchers, led by Prof.
Andrew Tomkins, studied 21 asteroid impact craters from a 40-million-year period known as the Ordovician impact strike. (The Ordovician period of Earth’s history lasted from 485 million years ago to 443 million years ago.) They noticed “that all craters fall in an equatorial band,” suggesting the material, known as L chondrite, fell from an equatorial orbit.
“We therefore propose that ...
a large fragment of the L chondrite parent body broke up due to tidal forces during a near-miss encounter with the Earth,” they write in the paper. “Given the longevity of the impact spike and sediment-hosted L chondrite debris accumulation, we suggest that a debris ring formed after this break up event, from which material de-orbited to produce the observed crater distribution. We further speculate that shading of Earth by this ring may have triggered cooling into the Hirnantian global icehouse period.
” So not only could there have been a pretty ring system orbiting our planet — at least until it started raining down in equatorial regions — but it may have also affected the climate, providing additional shade and cooling the Earth, bringing about the coldest ice age of the last half billion years. The researchers also looked at impact craters on the moon and Mars, finding no evidence of a similar spike. This would suggest that whatever meteorites fell to Earth at that time did not affect even our closest neighbour.
Nor did the impact fragments originate in the asteroid belt, which “ would be expected to affect Mars more than Earth,” they wrote. They also note that such an event would not happen often, since it would have to involve an asteroid approaching the Earth at a very specific velocity. “T he small size of the orbital window that such a body would need to pass through to break up in this way means that such events are very rare; this is consistent with the extraterrestrial chromite data, which suggest that this has happened only once in the last 540 million years and probably longer.
” Finally, the paper points out that the ice age that may have been caused in part by the ring “would create the need for adaptation in living organisms, potentially providing an explanation for the Great Ordovician Biodiversification Event.” This was an explosion of life forms at about the same time. Earth’s ring, if it existed, may have been responsible for the changes that took place in life on our planet hundreds of millions of years ago — and, by extension, everything that came after, including us.
Postmedia is committed to maintaining a lively but civil forum for discussion. Please keep comments relevant and respectful. Comments may take up to an hour to appear on the site.
You will receive an email if there is a reply to your comment, an update to a thread you follow or if a user you follow comments. Visit our Community Guidelines for more information. Three buzzed-about beauty products we tried this week.
Here’s everything you need to know about the sale Comfortable options for all preference styles Shop the collab in two new limited-edition colours. Sports Illustrated model, Reitmans ambassador talks body positivity and more. 365 Bloor Street East, Toronto, Ontario, M4W 3L4 © 2024 National Post, a division of Postmedia Network Inc.
All rights reserved. Unauthorized distribution, transmission or republication strictly prohibited. This website uses cookies to personalize your content (including ads), and allows us to analyze our traffic.
Read more about cookies here . By continuing to use our site, you agree to our Terms of Service and Privacy Policy . You can manage saved articles in your account.
and save up to 100 articles! You can manage your saved articles in your account and clicking the X located at the bottom right of the article..
