a working model of the known universe
Click the offline world map, search for an address when online, use your device, or enter exact coordinates. You can reopen this chooser at any time.
Address search is optional. Only when you press “Search online” is that text sent to the Photon geocoder; the map and coordinate controls stay fully offline.
Every total solar eclipse from 26 August 2026 through 26 August 2126 is calculated here, alongside lunar eclipses, planetary oppositions and curated mission milestones. Choose one to set the exact UTC instant and move the camera. Solar eclipses open on the Sun–Moon–Earth alignment; the observing view then moves to the calculated peak location.
A single-file, working model of the Solar System and the known universe — real orbital mechanics, real positions in time, and a continuous zoom from a lander’s footprint to the edge of the observable universe.
The Sky layer contains exactly 913 stars brighter than magnitude 4.5 from HYG v4.1, with J2000 right ascension, declination, visual magnitude and proper motion, plus colour index where catalogued. The 88 named constellation overlays are angular sky figures, never fake physical connections between stars at different distances. The IAU standardizes constellation regions and names; it does not prescribe one official set of stick figures, so these are explicitly labelled Western figures.
The Moon, its illuminated phase, observer parallax, and Io, Europa, Ganymede and Callisto now share date-deterministic J2000 vectors and sampled orbit guides from the embedded Astronomy Engine. Its published design target is approximately one arcminute for supported astronomical calculations; this model is educational, not a spacecraft-navigation product. Calculated eclipse and opposition cards preserve their computed UTC instant. Eclipse dates are cross-checkable against NASA’s Five Millennium Catalog; far-future UTC peak times depend on the adopted ΔT model and should be understood as predictions that can differ by minutes between authorities. Solar-eclipse cards first use a side-on alignment view with enlarged bodies and compressed distance, then offer a topocentric path view whose Sun and Moon directions and angular sizes are calculated for the peak location. Minor-moon phases remain illustrative circular motion, but their published mean orbital radii and body sizes participate in the true-scale modes. Local moon-system spacing stays expanded whenever visual body sizes are active; it becomes physically scaled only when both True sizes and True orbits are on. This prevents an inflated planet from swallowing its moons while keeping the mixed display modes usable.
The Sun, eight planets and Pluto use date-specific heliocentric J2000 state vectors from Astronomy Engine. Each planet guide is an instantaneous osculating orbit derived from that same live position and velocity, so the marker lies exactly on its guide. Perturbations make that smooth two-body guide evolve with time; it is not a propagated SPICE trajectory. The Moon and four Galilean moons use the same shared-state method. The 1800–2200 control is retained for exploration; accuracy varies by body and epoch. Halley follows a fitted 76-year retrograde ellipse. Spacecraft curves are reconstructions anchored to real encounter dates, not mission-grade SPICE trajectories.
Planet geography and object coordinates are data-led. Galaxy and nebula portraits are high-resolution rendered depictions built from published structure, not photographs. Their crisp filaments, dust lanes and wavelength-inspired colours are visual interpretation, not extra measured detail. Milky Way dust, the faint ambient star field, the Oort cloud and cosmic-web filaments are illustrative density fields. Deep-sky distances are compressed beyond the local neighbourhood so the continuous universe remains navigable; empty regions are left empty rather than filled with invented objects.
DESI survey overlay: 669,377 galaxies and quasars from the DESI EDR Visualization and Outreach Catalog are embedded as quantized sky directions plus DESI-fiducial comoving radii inferred from measured redshifts. Point colour encodes tracer class, not apparent colour. This optional overlay is hidden in the normal universe view. When selected, its 20 observer-centred wedges show the survey footprint: gaps mean “not measured in this release,” not “empty universe,” and the wedges are not physical rays or cosmic filaments. Marker size and apparent density are not physical, and the illustrative cosmic-web field is hidden while this measured overlay is selected. The complete catalogue remains embedded; this device may draw a regular subset to protect frame rate. Current DESI DR1 contains 18.7 million useful spectra, but its full 20.8 GB redshift catalogue is cited rather than mislabeled as present in this offline file.
🌍 Sky places the camera at your chosen latitude and longitude. The adjacent Location control can change the observer at any time without leaving Sky mode. The embedded Natural Earth map and manual coordinates work offline; device geolocation, Photon address search and the external Google Maps check happen only after an explicit click. An applied observer is retained in browser local storage until you use “Forget saved location.” Earth rotation, precession, nutation and the observer vector are calculated for the exact UTC instant. The Moon includes topocentric parallax and a phase-rendered terminator. A daylight atmosphere with twilight, eclipse-aware darkening and an adjustable light-pollution level is drawn (and can be toggled off). Atmospheric refraction is not yet applied, so objects near the horizon sit at their geometric altitudes.
Astronomy Engine, Don Cross, pinned commit 865d3da7 (MIT) · HYG Database v4.1, David Nash/Astronexus, pinned commit 3bf37f4 (CC BY-SA 4.0) · Western figure data derived from d3-celestial, Olaf Frohn (BSD-3-Clause) · JPL/NASA mission archives and Standish mean elements · NASA/IPAC NED · Messier, NGC and IAU nomenclature. Three.js is MIT-licensed. Required third-party notices, source URLs and modification notes are embedded in this file’s source. Natural Earth’s 1:110m land geometry is public domain; optional place search uses Photon/OpenStreetMap and visibly credits OpenStreetMap contributors. Music is generated locally in your browser.
Deep-sky visual references: NASA and ESA Hubble/Webb galleries, Chandra and Spitzer releases, and STScI’s MAST/Hubble Legacy Archive. These references guide morphology, dust placement, star-forming knots and wavelength-inspired palettes; their pixels are not used in the scene. Infrared, ultraviolet and X-ray colours are representational translations, not what an unaided human eye would see. The explorer makes no network request to render these objects.
Catalogue hierarchy: NASA/IPAC NED, SIMBAD, VizieR, Gaia and SDSS are the preferred authorities for identity, coordinates, redshift, distance and classification; NASA ADS and linked literature resolve disputed claims. Messier/NGC indexes and Go Astronomy’s notable-galaxy list are discovery aids only, never the final authority for a visible fact.
v16.7 · data cutoff 26 August 2026 · single-file offline build