stella nix

a high-resolution view of pluto in true color, showing the diversity of its terrain from around its north pole to just below the equator. just right of center, the left half of pluto's "heart" is called sputnik planitia, a sea of churning glacial nitrogen ice about 1400 x 1200 km in size. to its west are several mountain ranges, some peaks reaching over 6 km above the surrounding terrain. to the north, where the surface is a bit more yellowish, is a network of north-south trending canyons in pluto's north polar region. just east of sputnik planitia, smaller nitrogen ice glaciers spill out from the plain into more rugged terrain, and on pluto's eastern limb are many blade-shaped mountains possibly formed by sublimating methane ice. the dark area in the bottom left is belton regio, its color might be caused by a tar-like mixture of organic compunds, formed by chemical reactions involving methane and nitrogen driven by ultraviolet sunlight. there's a light north-south line in southeastern belton regio, which is a range of mountains capped by methane ice. these mountains are aligned with the north polar canyons, and may be part of a tectonic system circling much, if not all, of pluto's surface. belton regio is one of several similar dark areas forming a band around pluto's equator - their location might reflect processes related to pluto's seasonal climate. the rest of the surface is largely made up of cratered plains, with varying degrees of erosion and tectonic fracturing (image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker)

a close up view of pluto's crescent captured by new horizons about 15 minutes after closest approach. this view looks at terrain at the bottom of the previous image. the closer, oblique view and low sun angle highlights the topography. in the center are some mountain ranges, and just to the right is the flat expanse of southern sputnik planitia. this view also reveals many thin layers of haze in pluto's atmosphere. i would highly recommend opening this one up and zooming in - sometimes i just stare at it and imagine what it would be like to hike in those ice mountains! (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

one of the highest resolution pictures of pluto taken by new horizons, showing water-ice mountains (water ice is as hard as granite in plutonian temperatures) at the northwestern "shoreline" of sputnik planitia. this view is about 80 kilometers across, with the blocky mountains reaching heights over 2 kilometers. some layering is visible on the slopes of the mountains, while the flat plain of sputnik planitia has dark lines splitting it into roughly polygonal cells. nitrogen ice heated from below by pluto's internal heat rises at the centers of these cells, and descends at their edges. this constant cycle erases any craters that form on sputnik planitia on geologically rapid timescales. the rippled texture in this part of sputnik planitia is due to fields of dunes of solid methane sand, blown by wind in pluto's extremely thin atmosphere (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

the circular feature with the central depression in the middle of this image is wright mons, an unusual landform not quite like anything seen in the solar system before. it's 150 km across, and it rises over 4 km above the nearby plains, with its central depression dropping down by a similar elevation. there's only a single crater on the flanks of wright mons, suggesting that it's a geologically young feature. it's thought to be a cryovolcano, formed by eruptions of liquid water from pluto's interior, but the exact crypvolcanic processes at work are unclear. the mountain and its surroundings have lots of hummocky terrain with hills reaching hundreds of meters in height, and it's possible that wright mons may be built from these features in a manner similar to lava domes on earth (NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute)

sunlight scattered by layers of fine organic haze particles in the atmosphere forms a blue ring around pluto's night side, seen by new horizons as it departed from pluto. imagine what a sunset on the surface would look like (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

this is a true color image of pluto's largest moon, charon. charon is about half the diameter of pluto, and it's so massive relative to pluto that it doesn't orbit pluto directly. instead, pluto and charon both orbit their mutual center of gravity. in this orbital dance the two always show each other their same face (much like the same side of the moon always faces earth). this picture shows the side of charon facing pluto, while the first image of pluto above shows the side facing away from charon. one of the most striking features on charon is its dark, reddish north pole. it may have formed due to gases escaping from pluto's atmosphere and condensing onto the coldest part of charon's surface. there, sunlight caused reactions that formed a mixture of organic compounds, similar to the dark regions like belton regio on pluto. charon also has a vast system of cliffs and canyons running across its surface and roughly dividing its northern and southern hemisphere. billions of years ago, charon may have had a layer of liquid water in its interior, which would have frozen as charon lost its internal heat. water expands as it freezes, so this would've caused charon's crust to expand and split, forming the kilometers-deep fissures. cryovolcanic flows related to the freezing of the subsurface ocean may have erupted and resurfaced the southern plains, explaining why the terrain there is smoother and less heavily cratered than the north. the southern plains are also home to strange mountains apparently sunken, surrounded by moats (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker)