Mercury is the nearest planet to the Sun. It is also one of the tectonically active planets in our solar system. Despite its close proximity to the Sun, Mercury is active and has new geologic features on its surface.
Science News reports that Mercury has new cliffs and other features that are much younger than the planet. These new cliffs are small, only a few meters and have sharp edges. Such features on the cliffs make them recent additions to the planet's surface. The cliffs are believed to be only 50 million years old, much younger than the other features on Mercury's landscape.
The small scarps have been spotted by NASA's Mercury Surface Space Environment Geochemistry and Ranging Spacecraft or MESSENGER in short. The MESSENGER spacecraft detected the new cliffs on its final 18 months of orbit around the planet, according to Phys Org. The MESSENGER mission ended with the craft intentionally crashing on Mercury's surface last April 30, 2015.
The small scarps found means that the planet's surface is still fracturing as it slowly contracts and cools. The planet is shrinking as it slowly cools, Sean Solomon, planetary scientist at Columbia University explains. Other planets have gone through the same process though evidence of it has long since faded due to atmospheric conditions. Mercury's scars are still visible since it doesn't have any atmosphere.
Other scientists though are not fully convinced that the new scarps seen could be related to the shrinking of Mercury. Paul Byrne, planetary geologist at North Carolina State University, says that without more analysis on the newer scarps and how they relate to the older formations, it would be hard to conclude what they really are. The new scarps could be produced in other ways such as shifting rubble or shockwaves created by asteroids.
Smithsonian senior scientist Thomas R. Watters is lead author and principal investigator of the research. He says that based on analysis of the MESSENGER images, the scarps found on Mercury could be compared to the ones found on the Moon and attributed as well to its shrinking.
"The young age of the small scarps means that Mercury joins Earth as a tectonically active planet in our Solar System, with new faults likely forming today as Mercury's interior continues to cool," Watters says of Mercury's scarps.