Pluto is not a "dead" orb, but a place with a rich and possibly changing landscape, according to the first study based on this summer's flyby of the dwarf planet on the edge of our solar system.
"Pluto displays a diverse range of landforms, as well as evidence for geological and other processes that have substantially modified its surface up to geologically recent times," scientists said in their analysis published Thursday in the journal Science.
The light-colored, heart-shaped region in the photo above — called the Tombaugh Regio — gets its color from a thick layer of frozen methane, carbon monoxide and nitrogen. It's basically a giant glacier. The Tombaugh Regio — named for the man who discovered Pluto in 1930 — is about 1,100 miles wide and more than 900 miles north to south.
Pluto has mountains, some possibly a mile or more tall, which suggests the presence of a solid water-ice based bedrock, beneath the carbon monoxide, methane and nitrogen ices, and strong enough to support the weight of the mountains.
Parts of the planet are pockmarked with craters, especially the "densely cratered" region to the left of the Tombaugh Regio, called the Cthulhu Regio, which suggests that Pluto has been struck by other large objects throughout its history.
There are scarps and deep troughs in and above the Cthulhu Regio, some of which are more than 300 miles long.
This study said that "the rugged mountains and undulating terrain in and around" the Tombaugh Regio would have required "geological processes to have deformed and disrupted Pluto's water ice-rich bedrock."
Some of the craters show erosion, which the researchers take as a sign of geologic changes within the last few hundred million years. That's relatively recent in geological terms, and changes may still be continuing.
Much of the planet is red or deep yellow. Researchers think that's caused by a chemical reaction. A certain kind of ultraviolet light from the sun reacts with the methane on Pluto's surface, creating chemicals called "tholins," which then fall to the surface of the planet and give it a reddish color. This is different from the red color of Mars, which comes from the iron oxides on Mars' surface.
The answers scientists have found so far have raised more questions. What they haven't figured out is what actually powered the geological changes so long after the planet was formed.
The analysis was from images and data sent by NASA's New Horizons spacecraft, which made its historic flyby on July 14.