For all intents and purposes, Pluto and Earth don't have a lot in common. One is a planet, one is not (or at least not officially). One is an ice world, while the other is mostly water. One is red, the other blue. But black and white photos can obscure a lot of those differences. In the latest batch of images returned from the New Horizons spacecraft, Pluto looks a lot like home.
Do not be deceived, though. Those mountains aren't rocky like our own, they're made of solid ice. The dwarf planet can barely hang on to that thin, hazy atmosphere. And those smooth glaciers? They're made of nitrogen instead of water.
However, the most recent pictures provide new evidence that Pluto and Earth may be similar in more interesting ways—including having weather that changes from day to day, and something like a hydrological cycle. Only, instead of water, Pluto's hydrogen cycle would probably revolve around nitrogen.
Close-ups reveal flowing glaciers that carve out patterns in the icy plains informally named Sputnik Planum. The activity may come from the evaporation of ice from Sputnik Planum, which gets deposited on the mountains to the east and later streams back into the plains.
"We did not expect to find hints of a nitrogen-based glacial cycle on Pluto operating in the frigid conditions of the outer solar system,” said New Horizons' Alan Howard in a press release. “Driven by dim sunlight, this would be directly comparable to the hydrological cycle that feeds ice caps on Earth, where water is evaporated from the oceans, falls as snow, and returns to the seas through glacial flow.”
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