Pluto is a geologically active world. And we don’t know why. Amazing.


Pluto just got more interesting! Like, don’t get me wrong. Pluto. You were interesting before. But now with the news that you’re geologically active, and we have no stinking idea why? Now you’re a delicious mystery wrapped in a former-planet.


Data is streaming in from New Horizons after yesterday’s historic flyby of Pluto — and it’s painting a picture of the dwarf planet that we could have scarcely imagined.

For the first time ever, we can honestly say that scientists are shocked and baffled by a discovery. Pluto is a geologically active world. Moments ago, scientists working on NASA’s New Horizons team announced the presence of ice mountains and actively resurfacing planes in the first detailed look at the dwarf planet’s surface. Instead of a surface scarred by a history of bombardment, the first, highest-resolution image of the dwarf planet’s surface contains not a single crater. That means the surface of Pluto is young — really, really young.

Cratering rates inside our solar system are well-understood from detailed observations of our own moon and other exposed bodies around the solar system. To find no craters, not a single one large enough to see in this kilometers-per-pixel resolution images of Pluto’s surface, meaning that the surface is at most 100 million years old. That’s young in geological terms, much less in planetary terms.

To have a surface that young, Pluto must be an active world with processes that regularly resurface the terrain. The big question is: Where is this energy coming from?

We’ve seen active processes on icy worlds before, but those were all on tiny moons locked to massive gas giants. The accepted theory was that the constant pull of those behemoths were yanking on the planets in a form of gravitational massage, tidally heating them as a constant external energy driver. But Pluto is all alone in space, and while Charon is big for a moon, it’s nowhere near massive enough to create the kind of heat necessary to make Pluto into an active world.