Keplerian orbits computed from mean orbital elements (J2000 epoch, NASA Planetary Fact Sheets / JPL). Position markers show where each planet is on the selected date, calculated from Kepler's equation.
The orbits are ellipses in the ecliptic plane, tilted by each planet's inclination and rotated by its ascending node and argument of perihelion. This is the idealized two-body solution — the same math Kepler used in 1609.
All computation runs in your browser via Pyodide (Python compiled to WebAssembly). No server, no API calls. The math is yours to inspect.
The x arrow points at the vernal equinox, the First Point of Aries (♈). The floor of this box is the ecliptic, the plane of Earth's orbit, and z stands up from it. The frame is fixed to the stars at epoch J2000; it does not turn with the page.
The x marks on the three axis lines mark the grid: a small x at every grid step, a larger one at every second step. The ruler at the right shows those two steps with their values.
Source: NASA/JPL NAIF, Frames and Coordinate Systems tutorial (J2000 x axis at the equator-ecliptic intersection, the vernal equinox; the ecliptic frame shares it): naif.jpl.nasa.gov. The renderer rotates every pole into this frame (feature_renderers.js, poleBasis).
Distances here are in AU, astronomical units. One AU is about the distance from the Sun to Earth, fixed at exactly km.
Source: the International Astronomical Union, which fixed the AU at this length in its Resolution B2 of 2012: iau.org; "a unit of length approximating the Sun-Earth distance", its Measuring the Universe page: iauarchive.eso.org.