An artist’s rendering of the Earth surrounded by a temporary ring of debris 466 million years ago.Credit...Oliver Hull
The New York Times has a nice review of a study published in the journal Science Direct that postulates the Earth had a ring during the Ordovician Period, some 466 million years ago. There are numerous (21!) impact craters that date to the period. At the time, Earth was an island world, with life being mostly marine.
Scientists have long speculated about the origin of the Ordovician meteor event, when Earth was bombarded by space rocks at an unusually high rate, producing dozens of craters and sediments packed with meteorites. Previous research implicated a large asteroid that broke apart in the main belt between Mars and Jupiter and sent rocky shrapnel into the inner solar system, where it pelted our planet.
But what if this ancient object burst into pieces at our doorstep? Researchers led by Andy Tomkins, professor of Earth and planetary sciences at Monash University in Australia, envision an asteroid that passed within thousands of miles of Earth, close enough to be ripped apart by the planet’s gravity. The debris from the breakup then coalesced in a ring around the Equator, a scenario that may be linked to dramatic changes in climate and biodiversity at the time.
