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 n.