GRZEXP Staff: Max Wood
When the Earth shakes, most people recognize that as an earthquake. Earthquakes occur when tectonic plates under the earth rub together generating the shaking and opening of fault lines. The Moon has similar things that happen. The shaking on the moon is called Moonquakes.
This phenomenon was discovered in 1969 by accident after seismometers were planted on the moon. Nasa which is the united states space program stated “Between 1969 and 1972, Apollo astronauts placed seismometers at their landing sites around the moon.” and these machines revealed “There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface, probably caused by tides; (2) vibrations from the impact of meteorites; (3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and (4) shallow moonquakes only 20 or 30 kilometers below the surface”(science.nasa.gov).
The moon has several different quakes but most are caused by the same thing. Scientists have long agreed that the moon is shrinking every year. Nasa also states “The Moon is shrinking as its interior cools, getting more than about 150 feet (50 meters) skinnier over the last several hundred million years. Just as a grape wrinkles as it shrinks down to a raisin, the Moon gets wrinkles as it shrinks. Unlike the flexible skin on a grape, the Moon’s surface crust is brittle, so it breaks as the Moon shrinks, forming “thrust faults” where one section of crust is pushed up over a neighboring part.(https://www.nasa.gov)
Most moonquakes are caused by the moon shrinking. Every year moonquakes are happening. Most moonquakes are not as strong as earthquakes but some can last for up to an hour. Earthquakes are a lot more common than moonquakes but earthquakes happen because of tectonic plates. Moonquakes are much more rare and interesting. They continue to impress countries and nations across the globe.
Featured Image Credits: https://commons.wikimedia.org/wiki/File:The_First_Quarter_Moon.png