Earth once had 26 hours in a day, then an explosion changed everything
Produced by: Tarun Mishra
Credit: Getty Images
Moon's Drift
Researchers have discovered that Earth's days once extended by more than two hours, due to the moon drifting farther away from Earth during two distinct periods in the planet's history. This shift was caused by the moon's effect on Earth's spin.
Moon's Effect on Earth's Spin and Day Length
The moon's gravitational pull causes it to gradually move away from Earth. As the moon moves, it pulls energy from Earth's rotation, slowing the planet’s spin and lengthening the duration of its days. This gradual process impacts the length of days over time.
Study on Tidal Forces and Day Length
A study led by He Huang from Chengdu University of Technology examined rock layers called tidalites, dating between 700 million and 200 million years ago. These rock formations record tidal activity and help scientists understand the relationship between Earth’s spin and tidal forces.
Impact on Evolution and Life's Diversification
One key period, between 650 million and 500 million years ago, coincided with the Cambrian explosion, a time of dramatic diversification of life. The study suggests that longer days and increased sunlight exposure may have contributed to significant oxygenation events that promoted evolutionary changes.
Periods of Glacial Expansion and Earth's Spin
The second period of rapid rotational change occurred between 340 million and 280 million years ago, during a time when massive glaciers spread across Earth. However, the study indicates that glaciation had less impact on Earth's spin than previously thought, with most changes attributed to tidal forces.
Tidal Forces Driving Earth’s Rotational Changes
The researchers concluded that tidal forces, rather than glaciation events, played the most significant role in altering Earth's spin and day length. These forces are a direct result of the moon’s gravitational pull and its gradual movement away from Earth.
Caution in Interpreting Results
While the study suggests a connection between increased day length and life’s diversification, the researchers advise caution in interpreting these results. Further research is needed to fully understand the relationship between day length and evolutionary events.