PLUTO: WHERE EVERY FINDING IS A FIRST
The New Horizons probe did a single quick flyby on July 14, but NASA boasts of a “wealth of discovery” from those few hours. Pluto had been visible for years only as a glimmer of distant light.
Every detail is new — and surprising. Suddenly Pluto has an identity, not just a location at the edge of a map.
As a dwarf planet, Pluto was not expected to have a wide variety of different features. Yet it does: It has mountains in some areas and flat plains elsewhere. It has glaciers. It probably has ice volcanoes that have been active in the fairly recent past, likely producing partly liquefied water-ice, nitrogen, ammonia or methane.
“It just blew everyone’s mind. It has completely alien geology, at — 230C,” says Herd.
“There are things that are recognizable to us, like mountains and glaciers. But they’re not made of rock and water-ice. They’re made of water-ice as the rock, and nitrogen as the (glacier) ice.”
Next to Pluto, the big moon Charon “is so bizarre-looking. You have these two objects and they’re just so different-looking. It is challenging planetary geologists’ ideas about what’s possible in those cold reaches of the solar system.”
Charon has tantalizing features: mountains, plains, a big red splotch and a canyon four times the length of the Grand Canyon and twice as deep in places.
What emerges is also a picture of “active geology.” Pluto isn’t just a ball of inert rock, but rather a place where the surface is still changing. Some areas have rock four billion years old, while the surface of a plain shaped intriguingly like a heart is an estimated 10 million years old, almost yesterday compared to the solar system’s age.
If so, it formed long after Earth’s dinosaurs had disappeared, not long before the first hominids.
Pluto has a faintly blue sky visible at sunrise and sunset, a thin layer of methane and nitrogen, with little particles of carbon. Water-ice is also visible on some parts of the surface, while other parts of Pluto appear to have ice formed from other frozen gases.
And if material is melting and spreading out to make a smooth new surface, where does the heat come from? Pluto is too small to maintain a hot core like ours on Earth.