"Pluto was supposed to be a dead little world. Too far from the sun to have active geology, and too close to the Kuiper Belt to be covered in anything but craters. Then, in July, the New Horizons probe flew by. And bit after bit, pixel after pixel, its data confirmed that this planet was colorful and icy, with mountains and glaciers, spewing gases, blowing winds, and blue skies. Pluto isn't dead: It's awesome.
Now Pluto's awesomeness is officially part of the scientific record. Today—which happens to be the three month plus one day anniversary of the flyby—the journal Science published the first data from that historic occasion. On the surface, it's a New Horizons highlight reel. But beyond being a scientific nostalgia-gram, the paper ties together all the geophysical, atmospheric, and surface composition data from the probe, presenting Pluto, Charon, Hydra, Kerberos, Nix, and Styx as a vivid planetary system.
The Main Event
One of the first jobs planetary scientists do when looking at a new space rock is count the number of craters on its surface. Based on the probability of a meteor strike, they can use these craters to calculate the surface's age. Sputnik Planum—the western lobe of Pluto's big heart—is an ice plain the size of Texas, and it has zero craters. "None. Not even tiny ones," says Alan Stern, planetary scientist at the Southwest Research Institute in Colorado and principal investigator for the New Horizons mission. "That means it was born yesterday in geologic time span."
That basic observation changes everything, because it implies that Pluto has active geology. The world has other features seemingly created by internal movements. "If you look at the surface of Pluto, the range of landforms is astounding," says Stern: mountains, hillocks, scarps, glaciers, and canyons of different sizes, shapes, orientations, and ages.
It is important to note that what scientists call mountains are not exactly like the rocky structures commonly seen as desktop backgrounds here on Earth. "They are literally icebergs that poke out of the surface," says Hal Weaver, NASA's New Horizons project scientist, based at Johns Hopkins University Applied Physics Laboratory in Maryland. Icebergs most likely made out of water.
If you look closely at the mountains near Sputnik Planum's northwestern border, you can see what look like glaciers carving around these icy peaks. These glaciers are made from frozen nitrogen, which behaves like water ice on Earth because Pluto's surface temperature is around -395˚F…"
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