Let’s be real: we don’t know much about Pluto. We didn’t even “discover” it wasn’t a planet; we just changed our definition of “planet” to exclude it, after we realized there might be a hundred spherical objects of comparable size out there on the fringes of our solar system.
NASA’s New Horizons probe is set to give us our first close-up look at Pluto next summer, but until then these are the best pictures we have, courtesy of the Hubble Space Telescope. As you can tell, they aren’t very high-resolution. They tell us just enough to know that Pluto probably has surface ice that melts and refreezes over the course of the solar year, but they don’t tell us much else; almost anything could be sitting there on the surface, and we wouldn’t have a clue.
So when you catch wind of scientists credibly speculating that Pluto might have plate tectonics, “who cares?” might feel like a reasonable response—but this is actually a very important question. The existence of plate tectonics would bring us very close to proving that Pluto has an underground ocean kept warm by geological activity, much as Enceladus does (the key difference being that Pluto is nearly five times as large as Enceladus). And where there’s a warm liquid underground ocean, there’s a strong possibility of extraterrestrial life.
But more importantly than that? Think of those other hundred dwarf planets in our solar system that I mentioned in the first paragraph, and consider: Pluto just happens to be the first one we found. What if the outer solar system is chock full of little geologically-active dwarf planets with warm underground oceans? What would that tell us about the statistical odds of discovering extraterrestrial life in our own solar system’s backyard—not even to speak of the rest of the universe?