Till yesterday, Earth was the only tectonically active planet we discovered in our Solar System, a distinctive quality that's been linked to our planet's capability to host life. However, NASA has now found evidence that a small planet Mercury has the same geological movement beneath its surface, as well as shifting pieces of crust and increasing fault lines. The evidence came from pictures captured by the MESSENGER spacecraft, which zoomed in close to Mercury's surface throughout its last 18 months in orbit around the planet. The images displayed previously hidden fault scarps, cliff-like land-forms that look like steps, on the tiniest planet in our Solar System, and these scarps are small enough that researchers consider they must be geologically fresh. That proposes that Mercury is still shrinking, and Earth is no longer the only tectonically active planet in the Solar System.
A Smithsonian senior researcher at the National Air and Space Museum in Washington, DC, lead scientist Tom Watters said, "The young age of the tiny scarps means that Mercury joins Earth as a tectonically active planet, with new faults probably forming today as Mercury’s inner surface continues to cool and the planet contracts."
Showing scarps below:
The bad news is that in spite of its tectonic movement, Mercury rests pretty uninhabitable to life as we know it. With only an 88 Earth day orbit around the Sun, not much atmosphere, and temperature variations ranging from -173 degrees Celsius (-280 degrees Fahrenheit) at night to a boiling 427 degrees Celsius (800 degrees Fahrenheit) throughout the day, Mercury is not precisely an ideal spot for life to exist.
Despite all of this, the good news in is that by well understanding this tectonic movement on Mercury, we are going to gain better perception into where it happens, and how to spot it, possibly on worlds far beyond our Solar System. And apart from Mercury and Earth, symbols of tectonic activity have also been discovered on Jupiter's water-laden moon Europa. Europa's tectonic movement has not been confirmed, but as much as we can tell, Europa appears to be a considerable candidate for hosting life than Mercury is. That's because it is supposed Europa's tidal-lock with Jupiter keeps its sub-surface oceans warm enough to remain liquid. (But being a moon, that still marks Mercury the first planet in our Solar System other than Earth to have suspected tectonic movement.)
The scientists will now carry on the investigation of Mercury's overall magnetic field and surface movement to try to understand more of what is happening on the planet, there's also been evidence that the planet also involves quakes, just like Earth does.
NASA planetary science director Jim Green said, "This is why we search. For years, scientists supposed that Mercury’s tectonic movement was in the distant past. It is thrilling to consider that this tiny planet, not much larger than Earth's moon, is active even today."
The discoveries have been written in Nature Geoscience.