A full-colour closeup of what is thought to be the largest volcano on Pluto — and in the outer solar system — has been beamed back to Earth by the New Horizons spacecraft.
The suspected ice volcano, or "cryovolcano," has been nicknamed Wright Mons after the brothers who were the first to successfully fly a powered aircraft.
The mountain is 150 kilometres wide and four kilometres high (about two-thirds the height of Mount Logan, the tallest peak in Canada).
The image shows the volcano has only one impact crater on its surface. That suggests the surface was created rather recently, not allowing much time for meteors to hit it and leave more craters.
"This in turn may indicate that Wright Mons was volcanically active late in Pluto's history," says a NASA statement.
Another possible sign of volcanic activity is the strange distribution of red material that's "just sort of pasted on the side of the mountain," said the New Horizons team in an email to CBC News. It's not clear whether the red material was deposited in small patches, or the small patches are the result of a much larger patch being partially covered up.
Normally, red material on Pluto, thought to be deposits of organic or carbon-based compounds called tholins, appears in the bottoms of craters, along cliffs and in valleys between mountains. Tholins, which don't form naturally on Earth, are formed high in Pluto's atmosphere from nitrogen and methane when broken apart by ultraviolet light. They stick together into large particles that eventually get coated with ice and "snow" down to the surface.
Wright Mons is one of two suspected volcanoes on Pluto's surface spotted by the cameras on the New Horizons spacecraft last July 14, when it made the first ever flyby of Pluto and its moons. The spacecraft is still gradually sending back images and data captured during the flyby.