A recent study has revealed that the smallest planet in the Solar System is progressively shrinking as heat escapes from its core and new cracks appear on its surface.
Scientists have recently discovered that Mercury, the smallest planet in the Solar System, is getting smaller, as reported by Live Science. According to the findings, this planet closest to the Sun has been gradually cooling and contracting over many millennia, creating “giant scars” on its surface as its rocky exterior buckles due to the contraction. Geologists are uncertain about the exact timing of the formation of these scars or whether Mercury continues to create new ones as it continues to cool down – until now.
The image of the large rock walls formed by fault lines on Mercury is believed to be a result of the planet’s core contracting.
A new study published on October 2nd in the journal Nature Geoscience took a closer look at these scars and found small cracks that indicate they have certainly moved over the past 300 million years.
“Our team has found clear signs that many scars have continued to move geologically, even though they were formed billions of years ago,” said David Rothery, co-author of the study and a geologist at the Open University in the UK.
“This is similar to wrinkles forming on a baked loaf of bread, except that Mercury contracts because it’s getting colder,” added Rothery.
The latest close-up images of Mercury were provided by NASA’s Messenger spacecraft, which orbited the planet for over a decade from 2004 to 2015. The research team discovered features known as “scarps,” a geological term for small parallel cracks adjacent to large fault lines, right next to the scars on the surface. Scarps form as the large fault lines attempt to bend a rigid rock.
“If you try to bend a piece of baked bread, it can crack in a similar way,” explained expert Rothery.
The research team found 48 confirmed scarps and an additional 244 potential scarps.
They determined the age of these rock formations by using information about the rate at which dust particles (generated from asteroid impacts) obscure geological features on Mercury’s surface. Based on the degree of blurring in the images, the research team calculated that they are approximately 300 million years old.
The movement of these rock walls not only creates scarps but can also cause earthquakes on Mercury, similar to moonquakes recorded on the Moon, referred to as “moonquakes.” In fact, the Moon is believed to be contracting and has a “wrinkled” surface similar to Mercury. This is confirmed based on data from seismometers on the lunar surface.
Unfortunately, there are no such instruments on Mercury. However, Europe’s upcoming BepiColombo mission is set to begin orbiting this small planet in 2025, with hopes of providing more information about Mercury’s geology, including a clearer view of its “wrinkles.”