Mercury Is Still Shrinking And It's Giving The Planet Wrinkles: Study

A new planetary research has suggested that the planet Mercury is still shrinking and getting more wrinkles as it does. Scientists have known that Mercury, the smallest planet in the solar system, has been shrinking for billions of years. Mercury's radius may have decreased as much as 7km, models and observations indicate. However, it wasn't clear whether the planet was still actively shrinking. A new study, published in Nature Geoscience, has shown that it probably is. 

Study author Benjamin Man, UK's Open University (OU) research student, undertook a global survey of mercury using data from US space agency NASA's Messenger mission (2011-2015) and found small, fresh landforms called grabens. "Our discovery of so many grabens is significant as it indicates that not only has Mercury's tectonism been active recently, but it is also widespread across the surface of the planet," Mr Benjamin said, as per The Independent.  

"This is important as it confirms that global contraction is ongoing and raises questions regarding the thermochemical properties of Mercury's interior," he added. 

According to the outlet, scientists explained that Mercury, like any other planet, is losing heat, and as its internal rock and molten metal have gotten cooler, its inside has shrunk. Because of this, wrinkles have appeared on the planet's surface - formations known as "scraps". 

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Researchers used these scraps to prove that the planet has shrunk even more. To show that these scraps are still moving today, they turned their attention to grabens, which are small, shallow landforms that appear after scraps move about. The researchers measured the depths of the grabens by looking at the length of the shadows they cast and calculating the position of the spacecraft and the position of the sun. Then they calculated how long it would take them to infill and consequently found that many of the grabens likely formed in the past hundred million years. 

This suggests that the latest movement must have happened equally "recently," the study authors said. They stated that their study provides strong evidence for continued global contraction into the present day. 

Now, the next step will be the arrival of a space probe called BepiColumbo, which launched in 2018 with two satellites to study the planet's surface from different angles. The probe took a picture of Mercury while flying by the planet in 2021, but it is due to return to take higher-resolution pictures in late 2025, or early 2026. The hope is that these pictures could provide even more information about Mercury's geology.