The Geography of Pluto by Christopher DiRaddo

A polygonal convection cell structure is visible over much of the planitia.

Sputnik Planitia appears to be composed of ices more volatile, softer and more dense than the water-ice bedrock of Pluto, including nitrogen, carbon monoxide and solid methane. Geologic map of Sputnik Planitia and surroundings ( context), with convection cell margins outlined in black Soft-ice plains and glaciers These rapid changes probably relate to seasonal condensation and sublimation of portions of Pluto's atmosphere, amplified by Pluto's extreme axial tilt and high orbital eccentricity. Pluto's overall redness also increased substantially between 20. Pluto's surface color changed between 19: the northern polar region brightened and the southern hemisphere darkened. New Horizons data suggest equally variable surface ages for Pluto, with ancient, dark, mountainous terrain (such as Cthulhu) occurring alongside the bright, flat, effectively craterless Sputnik Planitia and various terrains of intermediate age and color. Pluto's color is more similar to that of Io with slightly more orange, significantly less red than Mars. The color varies between charcoal black, dark orange and white. Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn's moon Iapetus. Maps produced from images taken by the Hubble Space Telescope (HST), together with Pluto's light curve and the periodic variations in its infrared spectra, indicate that Pluto's surface is very varied, with large differences in both brightness and color, with albedos between 0.49 and 0.66. Distribution of volatile ices is thought to be season-dependent and influenced more by solar insolation and topography than by subsurface processes. The face of Pluto oriented toward Charon contains more solid methane, whereas the opposite face contains more nitrogen and solid carbon monoxide. More than 98 percent of Pluto's surface consists of solid nitrogen, with traces of methane and carbon monoxide. Center is 180 degrees longitude (diametrically opposite the moon Charon). The portions of Pluto's surface mapped by New Horizons.

The Geography of Pluto by Christopher DiRaddo