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The New Horizons science team has released more results from the spacecraft’s July 14 fly-by, revealing the existence of what look like two giant ice volcanoes on Pluto, data that suggests the smaller moons spin like tops, and a census of Pluto’s craters that show them distributed very unevenly across the planet’s surface, suggesting that large parts of Pluto’s surface have been resurfaced and thus have been geologically active.
One discovery gleaned from the crater counts also challenges the most popular theory about the formation of objects in the Kuiper Belt.
Crater counts are giving the New Horizons team insight into the structure of the Kuiper Belt itself. The dearth of smaller craters across Pluto and its large moon Charon indicate that the Kuiper Belt likely had fewer smaller objects than some models had predicted. This leads New Horizons scientists to doubt a longstanding model that all Kuiper Belt objects formed by accumulating much smaller objects of less than a mile wide. The absence of small craters on Pluto and Charon support other models theorizing that Kuiper Belt objects tens of miles across may have formed directly, at their current—or close to current—size.
In fact, the evidence that many Kuiper Belt objects could have been “born large” has scientists excited that New Horizons’ next potential target – the 30-mile-wide (40-50 kilometer wide) KBO named 2014 MU69 – which may offer the first detailed look at just such a pristine, ancient building block of the solar system.
As always, the results here are significantly uncertain. They are giving us a glimpse into the geology of rocky planets far from stars, but only a glimpse. I guarantee that any theories formed from this data will be incomplete and will likely be proven wrong.