Days on Earth were only 19-hours long in the Precambrian era

A day on the planet remained constant for billions of years during the Middle age epoch, a study finds
Shubhangi Dua
Earth had a 19-hour day in the Middle age epoch
Earth had a 19-hour day in the Middle age epoch

Jason Blackeye / Unsplash 

Traditionally, a consistent trend has been observed by scientists who suggest the Moon has been moving away from Earth over the past three or four billion years.

There was a long period in Earth’s history when days were shorter and the moon orbited closer to the planet.

The study, published in Universe Today, was conducted by Ross N. Mitchell, a Professor of geoscience and geology at the Chinese Academy of Sciences, and Uwe Kirscher, a research fellow at the Institute for Geoscience Research at Curtin University, Australia.

The length of the day was five hours shorter than the 24 hours we currently experience. Geologists find that during the mid-Proterozoic era, a day used to be 19 hours long for approximately one billion years.

'Boring billion'

Also known as the ‘boring billion’, a period of relatively limited biological evolution coincided with Earth’s shorter days.

The study researchers said, “The accelerative torque of atmospheric thermal tides from solar energy balanced the decelerative torque of lunar oceanic tides, temporarily stabilizing Earth’s rotation”

In simple terms, the forces caused by the atmosphere's temperature and energy from the Sun helped counteract the forces caused by the Moon's pull on Earth's oceans, stabilizing the Earth’s rotation. 

Scientists highlight that it is imperative to gather data related to the length of days (LOD) during the Precambrian era. It would help in understanding the evolution of the Earth–Moon system in high temporal resolution. 

"We realized that it was finally time to test a kind of fringe, but the completely reasonable, alternative idea about Earth's paleo rotation," Mitchel said

The research provides a deeper understanding of the planet’s history and how the natural satellite has evolved over billions of years.

The study reports, “In contrast with their oceanic counterpart gravitationally excited by the pull of the Moon, atmospheric tides are thermally excited by the absorption of sunlight by water vapor and ozone, the largest of which is semidiurnal (half of a day).” 

The study suggests that due to the arrangement of the three-body system and Earth’s sense of rotation, the lunar semidiurnal oceanic tide applies a decelerative torque and the solar semidiurnal atmospheric tide applies an accelerative torque on Earth’s rate of rotation.

Scientists believe that the interaction between the Earth's atmosphere and the Sun's heat played a role in keeping the day length unchanged for a while.

The research aligns with the notion that rising oxygen levels and complex life on Earth were delayed until the stable resonance was disrupted due to climatic change, the geologists surmised.

The study was published on June 12 by Nature Geoscience and can be accessed here.

Abstract

We present statistical analysis of a compilation of observational constraints on the Precambrian length of day and find that the day length stalled at about 19 h for about 1 billion years during the mid-Proterozoic. We suggest that the accelerative torque of atmospheric thermal tides from solar energy balanced the decelerative torque of lunar oceanic tides, temporarily stabilizing Earth’s rotation. This stalling coincides with a period of relatively limited biological evolution known as the boring billion.

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