No shade on New Horizons intended, but I was talking about the early 2000's revolution in understanding of ice moons/ocean worlds, and that preceded the Pluto flyby by a lot.
replyIt was a valuable piece of corroborating evidence, but not shocking and unexpected in the way results from those three missions were. We had good reason to believe Pluto would look a lot like Triton, and it does.
Fair enough, though how common was that belief that Pluto would look like Triton? Before the first photos from New Horizons pretty much every artistic rendition of Pluto I'd seen was a solid ball of rock and/or ice, more like Ceres than Triton.
replyBoth were known to be Kuiper Belt objects, so it was expected there would at least be a family resemblance. I don't think anyone expected Pluto to be more active than Triton; that was certainly a surprise.
replyIf there are planetologists reading the thread, I'd love to hear a more authorative perspective than mine!