A live model of the solar system. Planet and moon positions come from published NASA/JPL orbital data and follow the real sky. The date and speed controls move the whole system in time; Easy mode compresses distances so everything stays visible, Accurate mode is true scale. Spacecraft follow their real recorded trajectories from JPL Horizons and appear only during each mission's dates.
Where a site supplies them, the small pictures in the sky are photographs, each placed in the real direction of its subject; the distance at which a picture floats is symbolic. Clicking a picture opens the photograph. Pins on Earth mark where the aurora and landscape images were taken. Comets are off by default and include well-known comets and the ones photographed in the gallery.
The Milky Way entry, above Solar System in the body list, swaps to a galactic view: a top-down sketch of the galaxy's measured spiral arms with Sagittarius A* at the centre, the Sun at its measured distance from it, and an arrow showing the direction of the Sun's orbit. Distances there are illustrative and the view does not follow the clock; Solar System or Escape returns to the planets.
Open source under AGPL-3.0-or-later. Copyright Giancarlo Erra.
planetary elements valid 1800 to 2050 (JPL)
Planet positions use the JPL approximate-positions algorithm with Table 1 Keplerian elements, valid 1800 AD to 2050 AD.
Moon orbits are approximate: circular-inclined propagation of JPL mean satellite elements at epoch 2000-01-01.5 TDB. Orbit eccentricity, node and periapsis precession are not modelled, and the stated Laplace reference planes are approximated by the ecliptic frame.
Comet positions propagate JPL SBDB osculating elements fixed at their stated epoch as unperturbed two-body orbits; accuracy degrades away from that epoch.
Spacecraft positions are linearly interpolated between sampled JPL Horizons state vectors and are shown only inside each mission's ephemeris span; the trajectory lines join the stored samples. Mars rover pins sit at each rover's published waypoint coordinates.
Body orientation (rotation axis and prime meridian) follows the IAU WGCCRE 2015 rotational elements with the 2019 correction. Earth and the Moon use the WGCCRE 2009 closed-form expressions: the 2015 report removed them without a closed-form replacement, referring to the IERS for Earth and to DE421 libration angles for the Moon.
Surface maps are public-domain USGS Astrogeology and NASA global mosaics, aligned to each body's WGCCRE prime meridian; per-map provenance and longitude conventions are in textures/SOURCES.md. Credits: NASA/JPL/USGS; NASA/JPL/Space Science Institute; NASA/JPL-Caltech/Space Science Institute; NASA/JPL-Caltech/Space Science Institute/USGS; NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/USGS; NASA/Goddard Space Flight Center Scientific Visualization Studio; NASA Earth Observatory. Uranus, Neptune and Deimos have no public-domain global map and keep a flat colour.
All values are copied from the sources above or derived from them by documented unit conversions; none are invented. Colours are presentational.