Earth Days Are Getting Longer As The Moon Gets More Distant Gradually

If you are one of those who doesn't find the 24 hours in day sufficient for your daily routine, there is good news for you. A group of scientists reconstructing the history of Earth using geological evidence has revealed the days on our planet have been getting longer.

According to their calculations, more than a billion years ago, when there were barely signs of life as we know it, a single day on Earth lasted just a little over 18 hours. Since then, it has increased by more than five hours or approximately one 74-thousandth of a second every year, the Guardian reported.

The group of researchers, from University of Wisconsin-Madison and Columbia University, found that the trend, which is expected to continue in the future, is a direct result of the moon’s action. Our only natural satellite has been moving away from us, resulting in a reduction of our planet’s rotational speed and increase in length of the day.

"As the moon moves away, the Earth is like a spinning figure skater who slows down as they stretch their arms out," study coauthor Stephen Meyers said in a statement.

Earth’s movement, the researchers said, is determined by the celestial bodies in its proximity such as the moon and other planets. Any change in the force exerted by these bodies can affect our planet’s orbital path around the sun and its rotation around and wobble on its axis. The variations can, therefore, affect the distribution of sunlight on Earth, driving climate cycles for long periods.

However, witnessing the impact of these variations on our planet’s climate rhythm was not that easy, particularly on a scale going past a few hundred million years. Rock records dating more than a billion years old were available but the lack of geologic means to study them with precision as well as the uncertainty of celestial bodies in our solar system made things complicated.

This is why study Meyers worked in conjunction with Columbia University's Alberto Malinverno.

The duo developed a sophisticated statistical method that linked astronomical theory with geological observation and tested two rock layers, one from the 1.4 billion-year-old Xiamaling Formation in northern China and other a 55 million-year-old record from Walvis Ridge, in the southern Atlantic Ocean. The results helped them look back at the history of the solar system as well as Earth’s geologic past, without any uncertainties.

In the results, the researchers discovered variations in Earth’s orbit, the distance between Earth and the moon, and how the length of a day changed over time. They found the moon moved approximately 44,000 kilometers (27,340 miles) away from Earth in the last 1.4 billion years and is currently drifting at a rate of 3.82 centimeters (1.5 inches) every year. At this pace, a single day on Earth could be 25 hours long in just 200 million years, the Telegraph reported.

The study, titled “Proterozoic Milankovitch cycles and the history of the solar system,” was published June 4 in the Proceedings of the National Academy of Sciences.