Orbital Atlas starts from NASA/JPL Horizons state vectors and computes the orbits of the Sun, the planets, the Moon, Ceres, Halley’s Comet and three spacecraft itself — with Newton’s law of gravitation and the Sun’s relativistic correction. After ten simulated years the Earth is about 1.4 km from JPL’s ephemeris; the test suite checks this on every build. Add nearly 25,000 real asteroids and Kuiper-belt objects, 9,096 stars from the Bright Star Catalogue and 37 nearby stars in 3D. Thirteen bodies can be cut open: the layers are to scale, with depth, density, temperature and how we know — seismology, gravity field or model. A badge always says whether you are seeing true scale or an enlargement. Surfaces are mission imagery from NASA, USGS and Hubble.