Mercury joins Earth as tectonically active planet

NASA made a short but substantial announcement on Monday: Mercury is tectonically active, joining Earth as the second tectonically active planet located in our solar system. The realization was made thanks to research funded by NASA, which found that Mercury — which is small, hot, and shrinking, the space agency says — is continuing to contract, resulting in small fault scarps that are "geologically young" and serve as signs of tectonic activity.

According to NASA, the discovery of these formerly unknown fault scarps was made by the Mercury Surface, Environment, Geochemistry, and Ranging (MESSENGER) spacecraft. Each small fault scarp is basically a small landform that looks something like small cliffs with resemblance to stairs. The small size is what leads researchers to believe they're not very old and were formed recently.

In order to have formed recently, Mercury would have to be tectonically active right now and in the process of contracting. The only planet known to have this feature, up until now, was Earth.

Though the announcement was just made, the data gathered by MESSENGER is not new — the MESSENGER spacecraft ended its Mercury investigation mission (which started in 2011 following the craft's 2004 launch) by crashing into the planet, as the space agency intended.

Before discovering these small scarps, researchers believed that Mercury wasn't tectonically active. A paper detailing the study will be published in Nature Geoscience next month.