A small window into a vast universe.

Orion is a location-aware sky explorer for learning what is above you.

How positions are calculated

Astronomy Engine calculates solar-system positions for your location and time. Catalog star coordinates use the J2000 reference frame and are transformed into the local sky. The app includes 5,044 stars, 88 constellations, and 32 bright deep-sky objects from D3-Celestial and its XHIP-based catalog. Read the catalog license.

What the view does not predict

The map uses geometric altitude and assumes a flat horizon. It does not model terrain, buildings, cloud, light pollution, atmospheric extinction, or long-term stellar proper motion. Rise and set calculations include the library’s standard refraction corrections. Symbols are enlarged for selection, not drawn to angular scale.

Your location and phone

Your selected coordinates and preferences are saved in this browser. Browser assistant access is off by default. If enabled in Display settings, browser assistants can read your exact selected location and change the map. GPS coordinates and motion readings are otherwise used locally; camera access is not needed. Nearby place names are found on-device from a compact GeoNames catalog. They identify the nearest populated place, not exact administrative boundaries. City-name searches are sent to Open-Meteo, whose results use GeoNames data. City report links contain the city identifier, selected time, and object name, rather than your GPS coordinates.

Content and observing

The observing library links to sources for further reading. Its instructions explain this app’s features and limitations. Always verify the selected place and time before comparing the map with the real sky. Never look at the Sun through unfiltered optical equipment.