An offline planetarium for Android
Most planetarium apps assume you have a signal. Planetary Explorer assumes you don't — at a dark-sky site, on a plane, in a classroom with no Wi-Fi. Everything is bundled on the device.
See Planetary Explorer →▶ Try it in your browser
What "offline" actually means here
- 41,411 stars and all 88 constellations, with figures and IAU boundaries
- 1,900 deep-sky objects — every Messier and Caldwell, plus bright NGC/IC galaxies, nebulae and clusters
- A Tonight planner: rise, transit, set and a 24-hour altitude curve for any object
- Sky events, eclipses, oppositions and meteor showers, computed on the device
- 20 worlds with NASA/USGS imagery, and a 244,625-place Earth gazetteer
Why it matters
An app that needs a connection fails exactly when you need it: at the eyepiece, in a field, on a mountain. Because the catalogue ships inside the app, the sky is always there.
No ads, no accounts, no tracking
The app contains no advertising and collects nothing. The one optional online feature — refreshing the Sun's active regions from NOAA — is off unless you turn it on.
Also in the app
Astrology
Birth charts, houses, aspects, synastry, transits and progressions — offline.
Teacher mode
Lesson tours, an offline quiz and printable worksheets for classrooms.
Telescope control
ASCOM Alpaca mounts on your own network: GoTo, Sync, abort, park.