Interactive globe of the outermost Galilean moon — the most heavily cratered body in the solar system, and its most complete surviving impact record. The base is the USGS controlled global mosaic from Voyager 1/2 and Galileo SSI imaging at 1 km/px. Callisto never differentiated fully and shows no trace of internal geology: everything on this globe is an impact, culminating in Valhalla, the ~3800-km multi-ring structure that is the largest of its kind known. Yet Galileo's magnetometer found the same induction signature as at Europa — an ocean, under a surface that has done nothing for four billion years. JUICE makes repeated flybys through the 2030s.
The sphere is rendered in Three.js at Callisto's mean radius, 2410.3 km, scaled to scene units. The base map is the USGS Astrogeology controlled global mosaic from Voyager 1, Voyager 2 and Galileo SSI imaging at 1 km/px, greyscale, with a single uniform tint at Callisto's mean colour applied — all structure in the rendered brightness originates in the data. Coverage varies from a few hundred m/px under the best Galileo passes to very coarse gap fill; seams are left unretouched.
The entries in Data/worlds/callisto/features.json are drawn from the USGS Gazetteer, whose Callisto names come from northern mythologies. The record is entirely impacts: the multi-ring structures Valhalla and Asgard with their bright central zones and concentric graben, the younger basins Lofn and Adlinda in the south, the ~600-km crater chain Gipul Catena — like Ganymede's Enki, a tidally disrupted comet — and the anomalous dome crater Doh at Asgard's centre. Local Galileo imaging shows a dark, sublimation-degraded regolith blanketing everything; the knobs and spires it leaves are below global resolution and are discussed in the linked literature rather than drawn.
Callisto is synchronous at 16.689 days, tidally locked with the sub-Jupiter point at 0° longitude. The research panel queries body_server.py at /api/callisto/latest; absent a server, the seed research.json and ADS search links are used. The engine, server and data schema are shared with the other Worlds globes.