The Moon has not always been at the distance from Earth that we are accustomed to today—and this fact is gradually changing scientists' understanding of our planet's past. Modern measurements show that our natural satellite is moving away slowly but steadily, a process affecting both the climate and fundamental astronomical processes. These changes have been unfolding for billions of years and have left clear imprints on Earth's geological history.
How the Moon's distance was measured
In the late 1960s, during the Apollo program missions, astronauts placed laser reflective panels on the lunar surface. Thanks to these, scientists can send laser pulses from Earth and measure their return time with extraordinary precision. The data show that the Moon is receding from Earth at a rate of approximately 38 millimeters per year. Although this rate seems negligible, on geological scales it leads to substantial shifts, such as:
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The slowing of Earth's rotation
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Changes in the stability and tilt of its axis "Even such a small annual displacement of the Moon, over time, leads to a redistribution of energy in the Earth-Moon system," notes geologist Alexei Trofimov.
Milankovitch cycles and the Moon's orbit
Significant evidence also comes from Milankovitch cycles, repeating patterns recorded in ancient rocks that are directly linked to climatic changes. These cycles reflect variations in:
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Earth's orbit
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Its axial tilt
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Orbital eccentricity The primary periods identified are approximately 400,000, 100,000, 41,000, and 21,000 years. Of particular interest is the 21,000-year cycle, which relates to the precession of Earth's axis and appears to be directly influenced by the distance of the Moon.
How the Earth-Moon system looked in the distant past
By analyzing these cycles, scientists have been able to reconstruct the Earth-Moon system as it was approximately 2.46 billion years ago. The findings indicate that at that time, the Moon was about 60,000 kilometers closer to Earth. According to NASA calculations, Earth rotated faster then, and a single day lasted only 17 hours. "Climatic cycles act as a planetary memory," explains climatologist Maxim Orlov. "They allow us to reconstruct not only the past climate but also the astronomical conditions that shaped it."
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