A spectacular sampling of imagery from NASA’s New Horizons spacecraft reveals mountains and water ice bedrock on Pluto, an active crust on its largest moon Charon and the first resolved views of the icy world’s tiny mini-moons.
A snapshot of Pluto shows fresh deposits of water ice bedrock and 11,000-foot (3500-metre) mountains, revealing evidence Pluto’s surface is one of the youngest in the solar system. These mountains likely formed no more than 100 million years ago, suggesting the close-up region — which covers about one percent of Pluto’s surface — may still be geologically active today. Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape. Photo credit: NASA/JHUAPL/SWRINew Horizons found few craters on the surface of Pluto’s Texas-sized moon Charon, evidence of recent geologic activity. A swath of cliffs and troughs stretching about 600 miles (1,000 kilometres) suggests widespread fracturing of Charon’s crust, likely the result of internal geological processes. The image also shows a canyon estimated to be 4 to 6 miles (7 to 9 kilometres) deep. In Charon’s north polar region, the dark surface markings have a diffuse boundary, suggesting a thin deposit or stain on the surface. Photo credit: NASA/JHUAPL/SWRITuesday’s New Horizons flyby revealed Pluto’s tiny moon Hydra. The first resolved image of the object shows it to be 28 miles long and 19 miles in diameter, and better images are to come. The observations also indicate Hydra’s surface is probably coated with water ice. Photo credit: NASA/JHUAPL/SWRI
In the latter part of June, Pluto is best seen low in the southern UK sky around 2am local time and reaches opposition on 7 July. The dwarf planet passes less than 1/20th of a degree south of naked-eye star pi (π) Sagittarii on 26—27 June in the deep twilight of the UK, but Southern Hemisphere observers will have the best views.
Now just five days away from its close encounter with dwarf planet Pluto, NASA’s New Horizons spacecraft beams back the first image to be received since the 4 July anomaly that sent the spacecraft into safe mode, indicating that all systems appear to be functioning normally. The flyby sequence of science observations is officially underway.
At half the diameter of Pluto, Charon is the largest satellite relative to its planet in the solar system. NASA’s New Horizons spacecraft has returned the best colour and the highest resolution images yet of Charon, showing a landscape covered with mountains, canyons, landslides, surface-colour variations and more — all evidence of a surprisingly complex and violent history.