Earth Had Ring System Similar To Saturn Roughly 466 Million Years Ago: Study

Like Saturn, Earth may have also had its ring system circling the planet 466 million years ago.

These rings seem to have existed during the Ordovician Period when the Earth's life forms and plate tectonics witnessed significant changes after a peak in meteorite strikes, a study published in the journal Earth and Planetary Science Letters said.

The researchers have based their hypothesis on the positioning of nearly two dozen impact craters -- all placed within 30 degrees of the Earth's equator. This signals that these meteoroids might have rained down from a rocky ring around the planet, the study said.

Andrew Tomkins, a geologist and professor of Earth and planetary sciences at Monash University in Melbourne, Australia, said it was "statistically unusual" getting 21 craters all relatively close to the equator. "It shouldn't happen. They should be randomly distributed," Tomkins, also the lead author of the study, told CNN.

Besides shedding light on the origins of the spike in meteorite impacts, the latest hypothesis further tries to answer an unexplained event in history -- the global deep freeze, which remains among the coldest climate events in the planet's history.

Near the end of the Ordovician, this period is considered one of the coldest in the last 500 million years, Earth.com reported.

Scientists have suggested the ring system might have cast a shadow over the Earth, thereby blocking sunlight and causing temperatures to drop on the planet.

Earlier, scientists suggested a large asteroid broke apart within the solar system and created the meteorites that hit the Earth during the Ordovician Period. However, Tomkins claimed such an impact could have likely randomly distributed the strikes like the craters on the Moon.

In the latest study, the researchers hypothesise that a large asteroid, measuring around 7.5 miles (12 kilometres) in diameter, had reached the planet's Roche limit -- the distance at which the celestial body gets enough gravitational pull to break the approaching body.

This may have taken place around 9,800 miles (15,800 kilometres) from the planet if the measurements of past rubble-pile asteroids are to be considered.

Tomkins claimed the asteroid might have been largely hit by other collisions.

He added that the right might have formed along the equator due to the planet's equatorial bulge -- similar to the ones of Saturn, Jupiter, Uranus, and Neptune.