Interactive globe of Pluto's companion — at half Pluto's diameter, the largest moon relative to its primary, and with it the only true binary planet system explored. The base is the New Horizons LORRI/MVIC global mosaic at 300 m/px from the July 2015 flyby. Coverage is that of a single pass, exactly as on the Pluto globe: the encounter hemisphere is sharp, the far side is approach-resolution, and the terrain south of the terminator is rendered black. What the flyby showed was a moon torn nearly in half by its own freezing ocean — the belt of chasmata that girdles it — with the smooth cryoflow of Vulcan Planum to the south and the red tholin cap of Mordor Macula, painted by Pluto's escaping atmosphere, at the north pole.
The sphere is rendered in Three.js at Charon's mean radius, 606 km, scaled to scene units. The base map is the New Horizons LORRI/MVIC global mosaic at 300 m/px — the sibling product to the Pluto globe's base, from the same July 2015 flyby, and handled identically: panchromatic data with a single uniform tint at Charon's mean colour, encounter-hemisphere resolution falling to approach resolution on the far side, and the southern terrain that was in polar night rendered black rather than invented.
The entries in Data/worlds/charon/features.json follow the USGS Gazetteer, whose Charon themes honour the literature and craft of exploration — Serenity, Nostromo and Tardis Chasmata; craters Ripley, Organa, Skywalker, Vader, Spock; Kubrick, Clarke and Butler Montes. The geology they label is a freezing ocean's: the equatorial belt of chasmata records the expansion of Charon's interior as its ocean froze, Vulcan Planum to the south is the cryoflow that resurfaced a third of the encounter hemisphere, its 'moated mountains' (Kubrick Mons) standing where blocks foundered in the flow, and Mordor Macula at the north pole is methane escaped from Pluto, cold-trapped and radiolysed to red tholins — one world painting another.
Charon and Pluto are mutually locked: both rotate in 6.387 days, each holding the same face to the other, the fully despun end state of tidal evolution. The idle rotation renders that period's sense. Coordinates follow the Gazetteer; on the approach-resolution hemisphere the markers are placement aids. The research panel queries body_server.py at /api/charon/latest; absent a server, the seed research.json and ADS search links are used.