Our Moon is shrinking
What's the story
A recent study has revealed that the Moon is shrinking. The research team, led by Thomas Watters, a geologist and scientist emeritus at the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum, studied images taken by the Lunar Reconnaissance Orbiter Camera (LROC). They found over 10,000 young faults or cracks on the lunar surface. These findings helped them estimate that Moon's radius has decreased by 45 meters over a period of 400-800 million years.
Geological features
Geological features observed
The LROC observations revealed a range of geological features on the Moon's surface.
These included lobate scarps, which are long, curved structures formed by surface contraction, and small mare ridges or narrow "wrinkles" in the lunar landscape.
The research team found that these features were created as a result of the Moon cooling and contracting over time.
Tectonic differences
No tectonic plates on the Moon
Unlike Earth, which has about 15 major tectonic plates, the Moon has none.
It is a single-plate body with an outer shell that is one piece and only broken by faults or cracks created by contraction.
This means that instead of faults appearing at plate boundaries like on Earth, they are spread all over the lunar surface.
Lunar past
Mapping the Moon's history
By mapping these thousands of features, the researchers are piecing together a history of the Moon.
They found that some areas are more fault-ridden than others, with those having fewer faults having a thicker crust.
This led them to conclude that these stable areas with thicker crust were formed later in the Moon's history as its thick crust would have insulated its warm interior and prevented cooling, contraction, and cracking.