For millions of years, Earth has been giving its moon a massage. The effects of this massage — the constant pull of Earth’s gravity — only recently became apparent to scientists at NASA.The Earth’s own gravitational pull that keeps the moon in orbit is having a far more serious impact on the rocky satellite – it is tearing its surface apart.
Nasa scientists have identified more than 3,200 cracks, each several miles long and dozens of feet deep, crisscrossing the moon’s surface.Analysis of these faults, which are thought to be a result of the moon shrinking in size as its core cools, has revealed they are forming due to the gravitational tidal forces from Earth.
These small faults are typically less than 10 kilometres long and only tens of yards or meters high. They are most likely formed by global contraction resulting from cooling of the Moon’s still hot interior.
As the interior cools and portions of the liquid outer core solidify, the volume decreases; thus the Moon shrinks and the solid crust buckles. These globally distributed faults have emerged as the most common tectonic landform on the Moon.
An analysis of the orientations of these small steep slopes yielded a surprising result: the faults created as the Moon shrinks are being influenced by an unexpected source – gravitational tidal forces from Earth.
Researchers believe that as the moon’s contraction creates weaknesses in the lunar crust, the gravitational tug-of-war between Earth and moon stretches the faults along predictable angles. Our Earth is indeed massaging our Moon and shrinking it.
