Real positions
Every planet is placed by a real ephemeris: the open-source Astronomy Engine, built on the VSOP87 planetary theory, which its authors validate against NASA JPL Horizons to about one arcminute.
Universe simulator · Sky view · Tonight’s sky · Sky events
Explore the cosmos in real time
Fly through the Solar System, the nearest stars and the observable universe, then see what is in your sky tonight.
Loading the Solar System…
Star data: HYG Database v4.1 by David Nash, licensed CC BY-SA 4.0 and trimmed to 6,641 stars. Planet positions: Astronomy Engine by Don Cross.
The sky right now
Earth observatory
Weather Monitor
Live government Doppler radar from IMD India and NOAA, with forecasts.
Cyclone Simulator
Model storm genesis, steering flow, wind shear and ensemble tracks.
Earthquake Tracker
Real-time USGS quakes on a rotating 3D globe.
Space News
The latest NASA missions, rover updates and telescope discoveries.
What you are looking at
Real stars
Fly out to a 3D map of 6,641 stars from the HYG catalog: all of its stars within 65 light-years of the Sun and every star visible to the naked eye, at their measured distances and true colours.
Scale you can switch
Planets are tiny next to the gaps between them. “Fit all” compresses distances so Mercury and Neptune share one screen; “True scale” shows the real proportions. Sizes are always exaggerated.
Travel through time
Pick any date from 1600 to 2400, run time up to ten years per second, or play it in reverse to watch the planets retrace their orbits.
✦ Questions
About the simulator
How the Solar System simulator works, and what to expect from it.
An interactive 3D simulator that runs entirely in your browser. It has three scales. The Solar System shows the Sun, the eight planets, Pluto and the Moon at their real positions for any date between 1600 and 2400. Nearby Stars is a 3D map of 6,641 real stars around the Sun. Observable Universe is a logarithmic map from the Milky Way out to the edge of what we can see, with real distances and sky directions for the galaxies and clusters it shows. You can rotate and zoom, focus on anything, and fly between the scales.
Yes. Sky View shows the real sky from your location for any moment between 1600 and 2400: 6,641 stars, the Sun, Moon and planets with the Moon’s true phase, constellation figures, deep-sky objects, the Milky Way, a horizon and a sky that darkens through twilight. Search for any object, fly to it, and read its distance, brightness and when it rises and sets.
Yes. Tonight’s Sky shows, for your location, which planets you can see and how high they climb, the Moon phase with moonrise and moonset, sunset, sunrise and when the sky is fully dark. It also has a chart of the sky overhead that you can slide through the night.
The Sky Events calendar lists the next twelve months of eclipses, planets at their best, close meetings between planets, equinoxes and solstices, and meteor shower peaks. Add your location to see which eclipses you can watch, and add any event to your calendar.
Yes. The star map uses the open HYG Database (version 4.1, by David Nash), which combines the Hipparcos, Yale Bright Star and Gliese catalogs. This site keeps every star in it within 65 light-years of the Sun plus every star visible to the naked eye, and colours each one from its measured colour index. A star’s marker size shows its true luminosity, so a faint red dwarf is a small speck and a supergiant is large.
The catalog’s distances come from the Hipparcos satellite era and have not been updated to the newest Gaia measurements, so nearby stars can differ by a few hundredths of a light-year. Distances beyond about 300 light-years are rough, and the simulator marks them with a “≈”. To keep the sense of depth, stars far behind the ones you are looking at are drawn smaller and fainter than their true brightness.
Yes. Positions are computed in your browser with the open-source Astronomy Engine library, which uses the VSOP87 planetary theory (Pluto is integrated numerically). Its authors validate it against NASA JPL Horizons to about one arcminute. Only the sizes of the bodies and, in “Fit all” mode, the distances are adjusted so everything stays visible.
Not by default. Real planets are minuscule compared with the distances between them, so bodies are drawn larger than life. “Fit all” shows each distance as the square root of its value in astronomical units, so Neptune and Pluto fit on screen alongside Mercury; “True scale” shows real proportions. The Moon is always drawn at an exaggerated distance from Earth.
From 1 January 1600 to 31 December 2400. Use the date box for a specific day, or the speed menu to run time from real time up to ten years per second, forwards or in reverse.
Yes. Swipe sideways to rotate, pinch to zoom, tap a planet to focus it, and use the camera-angle buttons to tilt the view. Everything is calculated on your device and nothing is uploaded.
They are all still here, together in the Astrology menu in the footer: Kundli, horoscopes, matching, Panchang, numerology and the rest.