In the past, a day on Earth was 13 hours long, and that was because of the Moon

Photo byJavier MirandaonUnsplash

Researchers at the Friedrich Schiller University in Jena, Germany, studied the phenomenon of the Moon's gradual movement away from the Earth, as reported by the BBC. They observed that the Moon is moving away at a rate of 1.49 inches per year, making our days longer.

But why does the distance from the Moon have an impact on the length of the day? It's all a matter of tides," explains David Waltham, professor of geophysics at Royal Holloway, University of London, who studies the relationship between the Moon and the Earth.

In detail: The Moon exerts an attraction on the Earth that influences the phenomenon of tides. However, the Earth rotates on its axis faster than the Moon, which therefore "pulls" our tides back. This friction slowly eats up our planet's rotational energy, slowing its rotation, while the Moon gains energy, allowing it to move into a higher orbit.

Currently, the distance between the Moon and the Earth is 384,400 km. The work by researchers at the Friedrich Schiller University in Jena, Germany suggests that around 3.2 billion years ago, when the tectonic plates were just beginning to move, the Moon was only 270,000 km from Earth. Throughout its history, the Moon has moved away at a much slower rate than it does today.

Since the late 17th century, the average length of an Earth day has increased by about 1.09 milliseconds per century, which may seem small. But scientists point out that over the 4.5 billion years of Earth's existence, this extra time represents a profound change. Billions of years ago, a day on Earth lasted less than 13 hours, compared to 24 hours today.

Additionally, the current time frame appears to be increasing.

"The faster-rotating Earth shortened the length of the day so that [within a 24-hour period] there were two sunrises and two sunsets, not just one each as today"

explains geophysicist Tom Eulenfeld who led the study at the Friedrich Schiller University in Jena. This could have reduced the temperature difference between day and night and affected the biochemistry of photosynthetic organisms."

Despite the increase in distance, it is unlikely that the Moon will completely move away from Earth. Humanity can play a role in lengthening days by reducing the amount of water trapped in glaciers due to melting caused by climate change, because "ice essentially suppresses tides," notes David Waltham. According to him, our planet went through a particularly cold period 600-900 million years ago, known as the "Snowball Earth", during which the Moon hardly moved away at all.

Meanwhile, the astronauts of the next Artemis program, which should reach the lunar soil by 2026, will be able to say that they have looked further back at Earth than their predecessors in the Apollo program did.