Earth may once have had a planetary ring

It would have collapsed 450m years ago C ould Earth once have had a planetary ring like the ones around Saturn? Scientists from Monash University in Australia think so. In a recent paper they identify 450m-year-old craters that lie close to Earth’s historical equator. They propose these were caused by the collapse of a ring of debris (possibly the remnants of a large asteroid) that once circled the planet.

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