Thanks to the New Horizons probe's Tuesday flyby, there are, for the first time in history, some really good images of Pluto, and its moon, Charon. And they're pretty fascinating. They're showing details that we didn't know were there, and even some things we've never seen before, anywhere. There are ice mountains on Pluto that are roughly as tall as the Rockies, and on Charon there are chasms that may be six times deeper than the Grand Canyon.
Scientists had long theorized that Pluto was essentially a dead, frozen ball of ice, but remarkably the new images show a total absence of impact craters, even in a zoom-in shot of an otherwise rugged section. This suggests that Pluto has active geology still shaping its surface. John Spencer, a scientist at the Southwest Research Institute, ground control for the New Horizons mission, calls these findings "just astonishing", He's pretty sure that they're going to "send a lot of geophysicists back to the drawing boards."
The zoom-in covered a swath of Pluto that is about 150 miles (or 241 kilometers), wide. It shows details of a mountain range that's about 11,000 feet (3,353 meters) tall and tens of miles wide. Interestingly, it appears that these mountains aren't made of rock. They're made of ice. Of course, that far away from the Sun, many of the materials that are usually found in gaseous or liquid form on Earth are solid, rock solid. In Pluto's extreme cold methane and water may behave like rock does here on Earth. This appears to be the case with this mountain range, the peaks of which seem to have been pushed up from Pluto's subterranean bed of ice. Fascinating, yes, but even more significant as evidence of Pluto's active geology: these peaks appeared to be only 100 million years old, though Pluto is 4.5 billion years old.
"Who would have supposed that there were ice mountains?" asks project scientist Hal Weaver. "It's just blowing my mind."
Alan Stern, principal scientist for the New Horizons mission said of the new images: "I think the whole system is amazing. ... The Pluto system IS something wonderful."
In case you were wondering about the heart shaped area on Pluto, Stern and his team have named it the Tombaugh Reggio, in tribute to American astronomer Clyde Tombaugh. In 1930 he spied the cold, farthest out world on the edge of the solar system.
The new images have also allowed scientists to properly measure Pluto. With a diameter of 1,473 miles (2,370 kilometers), it turns out to be a bit bigger than was previously thought.
"We've tended to think of these midsize worlds ... as probably candy-coated lumps of ice," Spencer says. "This (the information shown by the new images) means they could be equally diverse and be equally amazing if we ever get a spacecraft out there to see them close up."