Is there water on Pluto?
We’re lucky to have Pluto. If people in the early 20th century hadn’t mistakenly thought Pluto was a major planet, much larger than it actually turned out to be, we might have declared it a boring icy body of the outer solar system and not gone to the trouble of sending the New Horizons probe to fly past it.
And we would mean we’d have missed out on the real Pluto — a beautiful icy body that continues to offer surprises months after New Horizons flew past it. This week, yet more new data from New Horizons revealed that Pluto has more water than originally thought. Water on Pluto isn’t like any water on earth: It’s so cold out there that it’s ice as hard as a rock.
Initially, scientists thought that there wasn’t much water on the surface of Pluto, because they were using a technique that could get confused by ice made from methane. A new technique offers a greater sensitivity to water ice, even when it’s mixed with other kinds of ices. It’s revealed that large sections of Pluto’s surface are rich in water. But other sections — including the western side of Pluto’s “heart” and far north — appear to be entirely water free.
Speaking of Pluto’s “heart” (informally named Sputnik Planum), another report from New Horizons this week suggests that some of the small hills on it are actually water-ice chunks floating like icebergs on a sea of frozen nitrogen. Pluto’s extreme cold makes ice behave as rocks do on earth, and nitrogen to behave like ice. The ice “hills” were probably carried down to Sputnik Planum by glaciers made of frozen nitrogen, and washed into the sea.