Pluto's 'Heart' Was Likely Broken by an Asteroid Long Ago

We've known since the Pluto flyby that Pluto had a heartshaped region, later named Tombaugh Regio. And we knew that the region was a study in contrasts. One side was old and cratered, while the otherside is so young many suspect it's still geologically active today. But New Horizons scientists are only now beginning to understand what might've formed the heart, and it points to a violent incident in the dwarf planet's past.

The likely agent that created the bizarre region known as Sputnik Planum was an ancient collision between Pluto and an asteroid the size of Manhattan. The 6.2 mile asteroid slammed into Pluto at some point, upending the region and possibly migrating it to its present location. 

The area itself likely has its strange, smooth appearance because it's still "warm" and thus prone to geological changes. "These blocks appear to have been removed from a subsurface layer, and they are now 'floating' in a large reservoir," New Horizons principal investigator Alan Stern told Stone. In other words, Sputnik Planum may be icebergs floating on a nitrogen sea.

This scenario adds to the body of evidence that, rather than a frozen relic of the early solar system, Pluto is still a geologically active world with some interior heat source powering it despite its vast distance from the sun. 

There's still a lot to learn from Pluto, and the return of flyby data isn't anywhere near completed. But we might have an answer now to what happened to its most captivating region, even if that answer comes with dozens more questions.