Scientists have just concluded the most comprehensive study on the relationship between the Earth and the Moon over the last 1.4 billion years. What they’ve found is that, 1.4 billion years ago, the days on Earth were lasting for only 18 hours. In fact, as we speak, the days are getting longer and longer as the Moon is moving away from us with about 1,5-inch every year.
The speed of rotation of our planet around its own axis is dictated, partly, by the Moon. 1.4 billion years ago, when the Moon was closer, the Earth was rotating much faster, while, on the other hand, in the present-days, the Earth is moving increasingly slower as the Moon is moving farther from us.
“As the Moon moves away, the Earth is like a rotating skater that slows down by stretching its arms,” said Stephen Meyers, a geoscience researcher and professor from the University of Wisconsin-Madison.
The length of days on Earth are influenced by the Moon and also by Milankovitch cycles
Stephen Meyers, one of the co-authors of this study which has been issued in the PNAS journal, also explained that the Earth’s rotation speed is also influenced by the gravity pulls of other space objects, besides the Moon.
However, the Moon and the other space objects, such as the Sun, are scientifically known as Milankovitch cycles. These variations are also determining how and where the light and warmth coming from the Sun in distributed on the surface of Earth, therefore these Milankovitch cycles are also influencing the climatic rhythm of Earth.
The study had to surpass over some challenges, such as radioisotope dating of geological samples, the lack of a clear history about the Moon, and the “solar system chaos” theory which says that any early slight variation in solar system’s moving parts triggered huge variations million of years later.
By decoding the solar system chaos theory during a study on sedimentary rocks of 90-million-year-old, Stephen Meyer and his colleagues were able to establish the history of the relationship between the Earth and the Moon.
The scientists concluded that 1.4 billion years ago, the days on Earth were lasting only 18 hours because the Moon was closer to our planet.