The Evolution of Earth’s Day Length: From 19 Hours to Present Time, Study Shows

A recent study has revealed that Earth had shorter days in the past compared to the present. According to research published in the journal Nature Geoscience, a full day on Earth about 2 billion to 1 billion years ago lasted five hours less than the current 24-hour day.

The study suggests that the shorter days were a result of the Moon being much closer to Earth during that time. As the Moon moved away from Earth, it gradually slowed down Earth’s rotation, causing the days to become longer.

Lead author of the study, Ross Mitchell, a geophysicist at the Institute of Geology and Geophysics of the Chinese Academy of Sciences, explained that over time, the Moon stole Earth’s rotational energy, propelling it into a higher and farther orbit from Earth.

To measure the length of ancient days, researchers used a geological method called cyclostratigraphy. This technique focuses on variations in rock sediment deposits and helps identify changes in Earth’s orbit and rotation known as Milankovitch cycles.

During the middle of the Proterozoic era, the Moon consistently drifted a certain distance from Earth, stretching out the length of the day by about 19 hours for 1 billion years. This period is referred to as the “boring billion” due to the relative stability of Earth’s tectonic activity, climate, and slower biological evolution.

The study also found that the longer duration of Earth’s days in the present is likely due to the influence of tides on the planet’s rotation. The Moon’s gravitational pull controls the tides in Earth’s oceans, slowing down the planet’s rotation. However, the Sun also exerts a gravitational pull through its atmospheric tides, which can accelerate Earth’s rotation.

Currently, the Moon’s tides are about twice as strong as those of the Sun’s atmosphere, meaning they have a greater effect on Earth’s rotation. However, during the “boring billion,” the Moon’s gravitational pull was weaker, resulting in more balanced tides from the Sun and the Moon.

This balance caused the length of Earth’s day to remain constant for some time. The study suggests that this prolonged period of a 19-hour day coincided with a slowdown in the increase of atmospheric oxygen during the mid-Proterozoic era, potentially contributing to a slowdown in the evolution of life on Earth at that time.

The findings of this study provide valuable insights into the history of Earth’s rotation and its impact on the planet’s climate and evolution. Further research in this field could help scientists better understand the dynamics of Earth’s rotation and its relationship with celestial bodies like the Moon.

How did the researchers estimate the Moon’s distance from Earth in the past and what data did they use

Th. This process, known as tidal acceleration, led to a decrease in Earth’s rotational speed and subsequently shorter days.

The researchers used advanced computer simulations to analyze the effects of the Moon’s proximity on Earth’s rotation. They found that when the Moon was about one-third it’s current distance from the Earth, a day on Earth lasted only 18 hours.

The Moon’s gravitational pull creates tidal forces on Earth, causing a bulge in the oceans that leads to tides. These tidal forces also exert a drag on Earth’s rotation, gradually slowing it down. As the Moon gradually moved away from Earth, the effect of these tidal forces became less pronounced, leading to longer days.

To estimate the Moon’s distance from Earth in the past, the researchers used data from lunar rocks brought back during the Apollo missions. They also utilized data from ancient tidal rhythmites, sediment layers that have distinct tidal deposits, to help determine the Moon’s previous position.

The findings of this study contribute to our understanding of Earth’s history and its relationship with the Moon. It provides insight into the mechanisms that shaped our planet and helps explain the changes in Earth’s rotation over billions of years.

Furthermore, this research has broader implications for our understanding of other planetary systems. The interactions between celestial bodies can significantly impact their dynamics and evolution. By studying our own planet, we can gain valuable insights into the processes at work in other planetary systems.

While it is fascinating to learn about Earth’s past and its shorter days, it is important to note that the Moon continues to move away from Earth today. However, the rate is much slower, and it is estimated that in about 50 billion years, a day on Earth will have increased to approximately 27 hours.

This study highlights the intricate interplay between Earth, its moon, and the forces that have shaped our planet’s history. It showcases the power of scientific research in uncovering the secrets of our universe and deepening our knowledge of the world we inhabit.