Open Planetarium

See the real night sky anywhere — no connection needed. Stars, planets, Messier objects, telescope FOV simulation, and a world-map location picker.

Open Planetarium is a beautiful, scientifically accurate virtual planetarium. The full sky works completely offline — all star, constellation, and deep-sky data is bundled with the app.

FEATURES

• Real star catalog: 8,920 stars down to magnitude 6.5 (HYG v4.1), with scientifically accurate star colors derived from each star's B-V color index • All 88 constellations: lines, names (English / Japanese / Latin), and official IAU boundaries • Solar system: the Sun, the Moon with phases and lunar age, and all 7 planets, computed with Meeus/Standish-compliant algorithms • Deep-sky objects: the complete Messier catalog (110 objects) plus major NGC/IC objects — 717 objects in total, with type icons • Powerful search: object names, constellations, M/NGC/IC numbers, planets • Object details: magnitude, coordinates, altitude/azimuth, and rise/transit/set times for your location • Time travel: set any date and time with the calendar dialog, scrub through the day with the time slider, or play diurnal motion at 60×/600×/3600× • Observing location: pick your spot on a zoomable world map with 1,250+ cities, search by country/city, enter coordinates manually, or use GPS • Survey imagery: overlay DSS2 sky survey layers (downloaded on demand and cached for offline re-display) • Equipment & field-of-view simulator: register telescopes, cameras, eyepieces and Barlows/reducers to preview framing and plan mosaic imaging • Milky Way rendering and adjustable light-pollution levels

PRIVACY

Your location is used only on your device to compute the sky above you — it is never sent anywhere. If location permission is denied, you can set the observing location manually.

Open Planetarium is free, open source (MIT), with no ads and no tracking.