What Pluto Has Not
What is most interesting about Pluto isn’t what we found but what we didn’t find in abundance, craters. Pluto doesn’t receive much light and heat from the Sun, it was expected to be geologically dead. Pluto and Charon must have internal heat sources, perhaps radioactive elements.
Pluto has a lower than expected albedo which lead to an under-estimation of it’s size. It’s size turns out to be 2370 km ± 20km. This makes it somewhat larger than Eris which is estimated to be 2320 km. I find it fascinating that a planet smaller than our own moon and so far out can show such variety and apparent activity. Pluto and Charon, like Uranus, orbit on their sides suggesting some sort of collision event in the past. They are tidally locked, like the moon is tidally locked to the Earth always presenting one side, but with Pluto and Charon, both bodies always show the same face to each other.
That both of these bodies show so much variety in their surface and recent activity leads me to wonder what else in the Kuiper built awaits our discovery. I’d really like to see a fly-by of Eris now that Pluto and Charon have proven to be such fascinating objects.