Soaring Over Pluto. Credit: NASA/JHUAPL/SSI/LPI
It’s been two years since NASA’s New Horizon spacecraft gave us our first closeup look at Pluto and its moons. These new videos use photos and elevation models of of Pluto and its largest moon, Charon, that offer a fresh new perspective of the features that make these objects so fascinating to look at. What’s more, they’re done from a vantage point even closer than a ride on New Horizons itself.
The Pluto flyover begins over the highlands west of the great, white expanse of nitrogen ice informally named Sputnik Planitia. We see the western border of Sputnik and the dark, cratered terrain of Cthulhu Macula, with blocky mountain ranges seen on the right. Pluto’s mountains are probably made of water-ice “bedrock” and rise as high as 11,000 feet (3,500 meters), a little shy of the Rocky Mountains. Only water freezes hard enough at Pluto’s distance from the sun to maintain a firm shape. Nitrogen ice is present, too, but it’s softer and not as stiff, undoubtedly one of the reasons it fills the dwarf planet’s broad expansive plains.
Notice the “red paint” splattered across the landscape. Simple organic chemicals like methane and ethane are bombarded by ultraviolet light from the sun and combine with nitrogen and other chemicals in Pluto’s atmosphere to form a reddish-brown “tholins,” a sometimes sticky residue that settles out of the atmosphere and coats large parts of the surface. Over millions of years, tholins can build up to form thick layers.
After passing over the mountains, we head north past the rugged and fractured highlands of Voyager Terra before turning south over Pioneer Terra, which displays deep and wide pits. Our journey ends in the far east in the bladed terrain of Tartarus Dorsa. “Blades” are bowl-shaped depressions with several-hundred-foot tall blade-like spires around the edge.
Soaring Over Charon. Credit: NASA/JHUAPL/SSI/LPI
The flight over Pluto’s largest moon, Charon, 753 miles (1,212 km) in diameter, begins high over the hemisphere New Horizons saw on its closest approach, then descends over the deep, wide canyon of Serenity Chasma. The view moves north, passing over Dorothy Gale crater and the dark polar hood of Mordor Macula. The flight then turns back south, covering the northern terrain of Oz Terra before ending over the relatively flat equatorial plains of Vulcan Planum and the “moated mountains” of Clarke Montes.
Charon is covered in water ice, where Pluto has much more nitrogen ice. It’s also home to a system of canyons, seen in the video, that’s far larger and deeper than the Grand Canyon. It’s still amazing to see so much once and possibly still-active geology on such icy worlds where the average surface temperature is –380° F (–229° C). You’d think that would be cold enough to put the kibosh on just about anything, but apparently not! Scientists are still trying to determine where the heat’s coming from that molds Pluto’s relatively young surface.
Pluto is in opposition to the sun this month and visible in larger amateur telescopes in the constellation Sagittarius in the evening sky. If you’d like to try to find it, click here for a recent article I wrote for Sky & Telescope.