An interactive globe of Saturn. The base is Björn Jónsson's cylindrical map — Cassini ISS imaging of September 2004 in the south, Voyager 2 imaging of 1981 in the north. The rings are a radial colour scan of the Cassini natural-colour mosaic PIA06175, calibrated to true radii and rendered at scale with shadows computed at run time in both directions. Named features are drawn from the atmosphere (the polar hexagon, the 2010–11 Great White Spot, Storm Alley) and from the ring system (the Cassini Division, the Encke Gap, the F ring); each opens a record. A literature feed is provided.
The globe is rendered in Three.js at Saturn's equatorial radius (60,268 km, scaled to scene units) and built as a true oblate spheroid at the ratio 54,364/60,268 = 0.9020376, each texture row placed at its own planetocentric latitude; compressing a sphere along the spin axis instead would place it at the parametric latitude and displace features by up to 3.0° (about 2,900 km). Saturn has no solid surface, and its banding lies beneath a photochemical haze, hence the low contrast of the base map: Björn Jónsson's cylindrical mosaic, southern hemisphere from 56 Cassini ISS frames of September 2004 (CB1 and BL1 filters, green synthesised), northern hemisphere from 31 Voyager 2 frames of 1981. Textures ship as Maps/textures/saturn_color_*.jpg.
The rings are a single annulus mesh from 66,900 to 141,000 km at the scale of the globe, with UVs remapped so that the texture coordinate runs radially. The texture (Maps/textures/saturn_rings.png) is derived rather than painted: a colour profile is sampled along the major axis of the Cassini natural-colour mosaic PIA06175, along which projected distance is proportional to true radius, then pinned to ring geometry by a piecewise mapping through ring-edge landmarks. The mosaic spans 74,565–136,780 km, so the B-ring edges, the Cassini Division edges and the Encke Gap fall within it while the D ring and the F ring are extrapolated. The alpha channel is set region by region from published normal optical depths, with the Colombo, Maxwell, Encke and Keeler gaps cleared at their measured radii, then modulated by the fine structure of the scan. Shadows come from an alpha-tested depth pass, in both directions and varying with the viewing geometry.
The named features in Data/worlds/saturn/features.json fall into two families. Atmospheric features are placed by latitude: the north polar hexagon, both polar vortices, the eruption site of the 2010–11 Great White Spot, Storm Alley and its Dragon Storm, the String of Pearls, the equatorial jet, and the Cassini orbiter's atmospheric entry point of 15 September 2017. Their longitudes are nominal, since the cloud field is close to axisymmetric, spot longitudes drift, and the System III radio period differed between the Voyager and Cassini epochs. Ring features are placed in the ring plane at their true radii — the Encke Gap, for instance, at 133,580 km. The research panel queries body_server.py at /api/saturn/latest (NASA ADS, with arXiv as fallback) and a per-feature endpoint; absent a server it falls back to the seed research.json and to ADS search links.
Ring radii are accurate to the calibration landmarks, quoted by the pipeline as better than ~300 km through the main rings. Atmospheric longitudes label latitude bands and are not ephemeris positions. The 2010–11 Great White Spot post-dates both epochs of the base map, so the marker records its eruption latitude rather than an imaged storm. The idle rotation uses the Voyager SKR System III period, 10 h 39 m 22 s; C-ring seismology gives an interior period of 10 h 33 m 38 s (+1 m 52 s / −1 m 19 s), shorter by 5 m 44 s; no Saturn longitude system is established with confidence.
Saturn is highlighted in cyan on a live map of the uniquely named solar-system bodies — planets, dwarf planets, named minor planets (26,061 as of June 2026) and comets — together with the interstellar objects and the escaping spacecraft, each at its current position and linked to its source record.
body_server.py