NASA LRO Discovers Earth is Massaging Our Moon and Causing Cracks

First Posted: Sep 16, 2015 06:54 AM EDT

It turns out that Earth may be "massaging" our moon. Scientists have found that Earth's gravity has influenced the orientation of thousands of faults that form in the lunar surface as the moon shrinks.

In August 2010, the researchers using images from NASA's Lunar Reconnaissance Orbiter's (LRO) Narrow Angle Camerica (NAC) found 14 cliffs known as "lobate scarps" on the moon's surface. Previously, 70 others had been found. Due to their random distribution around the surface, researchers concluded that the moon is, in fact, shrinking.

These small faults are typically less than 6.2 miles 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.

Global contraction alone should generate an array of thrust faults with no particular pattern in the orientations of the faults, because the contracting forces have equal magnitude in all directions. However, that's not what the researchers found.

"There is a pattern in the orientations of the thousands of faults and it suggests something else is influencing their formation, something that's also acting on a global scale-'massaging' and realigning them," said Thomas Watters, one of the researchers, in a news release.

In this case, the researchers' modeling showed that the peak stretches are reached when the moon is farthest from Earth in its orbit. If the faults are still active, the occurrence of shallow moonquakes related to slip events at the faults may be most frequent when the moon is at this point.

The findings reveal that these faults are the cause of interactions with our planet. This, in turn, may reveal a bit more about our planet's system.

The findings are published in the journal Geology.

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