The hills scattered across Sputnik Planitia
Processed image. Annotated photographic context plate from the 14 July 2015 flyby. The MVIC inset, acquired about 12 minutes before closest approach, has a native scale near 320 metres per pixel. North is up and light comes from the upper left. Hill chains and clusters motivate a buoyant-block interpretation; annotation and global context do not measure individual hill motion.
NASA/JPL image-use policy · credited mission imagery, resized to WebP
· Original image source · Image licenceSmall blocks lie among the patterns of a nitrogen-ice plain.
- World
- Pluto
- Case date or period
- Flyby observations · 14 July 2015
Look closer
New Horizons saw hill-like features within Pluto’s smoother plains and along their mountainous edge. The mission interpretation relates these blocks to water ice amid denser nitrogen ice.
Follow the evidence
Browse the annotated view and shoreline details to connect the proposed floating-hill interpretation with their spatial arrangement. A single image shows positions, not the motion itself.
Solid ice can circulate without melting
William McKinnon and colleagues tested whether heat from Pluto’s interior could drive convection through Sputnik Planitia’s solid nitrogen-rich ice. Their calculations reproduce broad surface cells under a sluggish moving lid, with warmer ice rising and cooler material returning downward. This provides a mechanism that could redistribute buoyant water-ice blocks and renew the plain. Cell dimensions and the scarcity of craters constrain the model; neither supplies a measured velocity for an individual hill. “Floating” here refers to density contrast within deformable ice, not a lake of liquid nitrogen.
The pond is a separate question
The small smooth feature in the frozen-pond photograph poses a different problem from the cellular plain. Its proposed former-lake interpretation requires an earlier climate with conditions permitting liquid nitrogen. McKinnon’s convection study instead concerns deformation within present solid ice. Keeping these questions apart lets you explore both possibilities without turning every smooth patch into a lake or every isolated block into a measured drifting iceberg.
Sources & further reading
- Pluto Mysterious, Floating Hills — NASA Image and Video Library / JPL
- The Mountainous Shoreline of Sputnik Planum — NASA Image and Video Library / JPL
- Pluto: On Frozen Pond — NASA Image and Video Library / JPL
- Convection in a volatile nitrogen-ice-rich layer drives Pluto’s geological vigour — McKinnon and colleagues — Original research paper / author preprint