An interactive globe of the Sun. The current live SDO full-disk image is deprojected onto the Earth-facing hemisphere; the far side carries a Carrington synoptic map. Nine wavelength channels sample the atmosphere from the photosphere to the flaring corona, and active regions are read from NOAA space-weather products at run time. A second live cap from STEREO-A covers a band of far-side longitude inaccessible to the Earth-facing disk. Each cap is timestamped.
The sphere is rendered in Three.js at the solar radius (695,700 km, scaled to scene units) in a body-fixed Carrington frame. A star has no surface to displace and no permanent map, so the relief and gazetteer slots of the Worlds engine are repurposed: choropleth layers become wavelength channels and named features become active regions.
Only the Earth-facing hemisphere is imaged at any instant, so the texture is assembled in two parts. The current full-disk image for the selected channel is retrieved from the Helioviewer API and deprojected in a fragment shader: for heliographic latitude φ and Carrington longitude λ the orthographic disk coordinates are x = cosφ·sin(λ−L₀), y = sinφ·cosB₀ − cosφ·cos(λ−L₀)·sinB₀, with visibility z = sinφ·sinB₀ + cosφ·cos(λ−L₀)·cosB₀ > 0. The sub-Earth point is the current (B₀, L₀), evaluated client-side from the Meeus solar ephemeris. The far side is filled by a Carrington synoptic texture assembled by Tools/build_world_layers.py from one rotation of daily frames; where that product is absent, the channel shows the live cap over a dark far side and carries a data-pending badge. Both layers are timestamped: the near side is current, the synoptic side up to 27.3 days old.
STEREO-A leads Earth in heliocentric longitude, the separation increasing at ≈22°/yr since the Earth flyby of 2023 August 12, so its SECCHI/EUVI imager covers a band of heliographic longitude inaccessible to SDO. For the four EUVI-matched channels (171→171, 193→195, 211→284, 304→304) the newest STEREO-A frame is resolved through body_server.py at /api/sun/stereo; the sub-spacecraft Carrington longitude and latitude (CRLN_OBS, CRLT_OBS) and the solar radius are read from the JP2 FITS header, and that disk is deprojected as a second live cap centred on the sub-spacecraft point. Where the caps overlap, the higher-resolution SDO near side is drawn on top; beyond the Earth limb STEREO-A supplies recent data in place of the synoptic map. STEREO-A telemetry is downlinked in batches, so this cap is hours to days old, as its timestamp records, and the plate scale and colour tables of EUVI differ from those of AIA. HMI, 1700, 131 and 94 Å have no EUVI counterpart and remain SDO-only.
Each channel corresponds to a height in the solar atmosphere: HMI continuum (photosphere) and magnetogram (line-of-sight B), then AIA 1700 Å (temperature minimum), 304 Å (He II, ≈0.05 MK), 171 Å (Fe IX, ≈0.6 MK), 193 Å (Fe XII, ≈1.2 MK), 211 Å (Fe XIV, ≈2 MK), 131 Å (Fe XXI, ≈10 MK) and 94 Å (Fe XVIII, ≈6.3 MK). The last two are listed in the order given by the manifest, which is not the order of peak response. The channel list, colorbars, formation temperatures and citations are read from Data/worlds/sun/layers.json, each entry carrying its Helioviewer layer string. HMI Dopplergram is not included; it requires JSOC rather than Helioviewer.
Active-region markers are placed by Carrington longitude and heliographic latitude from the NOAA SWPC solar_regions.json product, served through body_server.py at /api/sun/regions together with the GOES X-ray flare tally; selecting a marker returns its McIntosh sunspot class, Hale magnetic class and flare counts. The research panel calls /api/sun/latest, falling back to a seed list when the server is unavailable. The globe auto-rotates at a fixed presentation rate, not at the solar rotation rate. A single draped texture cannot shear, so differential rotation is rendered as a labelled latitude-band overlay evaluated from the Snodgrass and Ulrich (1990) Doppler rate Ω(φ) = 14.713 − 2.396 sin²φ − 1.787 sin⁴φ deg/day, giving sidereal periods of 24.5 d at the equator and 34.2 d at the poles.
The Sun is at the centre of a live map of the uniquely named solar-system bodies — planets, dwarf planets, the named minor planets (26,061 as of 2026 June) and named comets, together with the interstellar objects and the escaping spacecraft — each at its current position and linked to its source.
build_world_layers.py · feeds via body_server.py