Geology of Pluto

[1] When it did, Pluto was found to have remarkable geologic diversity, with New Horizons team member Jeff Moore saying that it "is every bit as complex as that of Mars".

[9] Distribution of volatile ices is thought to be season-dependent and influenced more by solar insolation and topography than by subsurface processes.

Pluto's surface color changed between 1994 and 2003: the northern polar region brightened and the southern hemisphere darkened.

[14] 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.

[16] A number of mechanisms are proposed to explain the absence of craters, including cryovolcanism (volcanoes erupting volatiles instead of magma), convective overturn, and viscous relaxation – processes that would erase negative topography.

Moores and his colleagues hypothesize that Pluto's penitentes grow only during periods of high atmospheric pressure, at a rate of approximately 1 centimeter per orbital cycle.

[20] Cutting through both Tartarus Dorsa and Pluto's heavily cratered northern terrain (and thus formed more recently than both) is a set of six canyons radiating from a single point; the longest, informally named Sleipnir Fossa, is over 580 kilometers long.

to be losing hundreds of tons of its atmosphere an hour to ultraviolet light from the Sun; such an escape rate would be too great to be resupplied by comet impacts.

Images of structures that imply upwelling of material from within Pluto, and streaks possibly left by geysers, support this view.

Ammonia-rich cryolavas appear to have erupted from Virgil Fossae and several nearby sites and covered an area of several thousand square kilometers; the fact that the ammonia's spectral signal was detectable when New Horizons flew by Pluto suggests that Virgil Fossae is no older than one billion years and potentially far younger, as galactic cosmic rays would destroy all the ammonia in the upper meter of the crust in that time and solar radiation could destroy the surface ammonia 10 to 10000 times more quickly.

[28] It is possible that such heating continues today, creating a subsurface ocean layer of liquid water and ammonia some 100 to 180 km thick at the core–mantle boundary.

[33][34] Pluto is proposed to have a thick water-ice lithosphere, based on the length of individual faults and lack of localized uplift.