About this model
Years run from −3000 to 3000. Year 0 is 1 BC, and −43 is 44 BC. Dates use the Gregorian calendar and UT. Positions are most exact from 1800 to 2050.
Planet positions use the VSOP87 theory (about 0.1 arcsecond for the planets across the whole date range), and the Moon uses the full main series of lunar theory. The 46 moons use JPL mean orbital elements. Eclipses come from the shadow cones of the Sun, Moon and Earth. Planet maps are real imagery. Zoom close in 3D and Earth, the Moon, Mars and Mercury load sharper map tiles for the area in view: NASA Blue Marble and Black Marble for Earth (to about 0.6 km per pixel), the NASA LRO camera mosaic with LOLA terrain for the Moon, the USGS Viking color mosaic for Mars and the MESSENGER mosaic for Mercury. The Sun and the other planets use maps from Solar System Scope (NASA and USGS data, CC BY 4.0), with Pluto from New Horizons. Saturn's rings are drawn from their measured structure. Moon maps for the larger moons come from the Stellarium project. Spacecraft paths are NASA JPL Horizons state vectors, and the dark spots on Jupiter are the real shadows of its moons. Constellation lines, names and Messier objects come from the d3-celestial data set (Olaf Frohn, BSD-3), and the place names are placed by hand from the IAU and USGS gazetteers. Stars are the HYG catalogue (Hipparcos, Yale and Gliese), about 83,000 down to magnitude 9, with their real colours; the Milky Way is NASA's all-sky star map. The Galilean moons use USGS Voyager and Galileo mosaics. In 3D each planet turns at its real rate on its real tilt, and Earth shows the correct day and night for the date. Dwarf planets and large asteroids use JPL Small-Body Database elements advanced as two-body orbits, so they are most exact within a few centuries of today. Small moons without a measured size are not drawn.