A star map for iPhone with nothing locked. Point your phone at the sky and see every star, planet, constellation, galaxy and satellite, plus what's worth looking at tonight.
By Open Apps Studio. No ads, no accounts, no paywalls, no "Plus" tier.
Every good star app on the App Store locks the useful stuff. Stellarium Mobile wants $1.99–$18.99 for moving time forward and the events calendar, Sky Guide sells "All Constellations" for $1.99 and subscriptions up to $249.99, Night Sky and Sky Tonight put tonight's best targets and reminders behind a subscription. One App Store review of Stellarium Mobile says it pretty well: "simply moving time forwards is a paid feature??"
Star Map gives you all of it, and the code is right here.
The sky
- Point your phone at the sky (gyroscope + compass, true north when location is on), or drag around with your finger.
- AR mode: the camera view behind the sky, with stars, lines and names drawn over the real thing.
- Stars to magnitude 8 offline, deeper (Gaia DR3) when online. Planets with real surfaces, the Moon with its phase, comets, 20,000 asteroids, satellites with today's orbits.
- All 88 constellations with lines, names and artwork, plus 34 other sky cultures (Chinese, Norse, Māori, Navajo, Egyptian…).
- Grids and lines (equatorial, azimuthal, ecliptic, meridian), atmosphere, light pollution (Bortle 1–9), landscapes, meteor showers, night mode.
Planning a night out
- Tonight: sunset, darkness, dawn, the Moon, a timeline of when each planet is up, visible satellite passes (ISS, Tiangong, Hubble, the bright ones), and the best deep-sky targets with real photos.
- Conditions: hourly cloud cover, humidity, wind and a 0–100 stargazing score for tonight and the next 6 nights (weather from Open-Meteo).
- Calendar: 12 months of eclipses (with local circumstances), meteor shower peaks, oppositions, elongations, conjunctions, Moon phases and seasons.
- Alerts: a notification 5 minutes before every visible ISS pass, and before the big sky events. Or tap the bell on any single pass or event.
Looking closer
- Tap anything for its card: where it is now, rise/set/transit, best time tonight, an altitude graph you can scrub, distance, magnitude, size, a Wikipedia summary.
- Path tonight: the object's track across your sky with hour marks.
- 3D view of the planets (lit and oriented as seen right now, with their moons) and of the ISS and Hubble.
- Eyepiece, camera, binocular and Telrad field-of-view overlays for your own gear.
- Telescope control over Wi-Fi (Stellarium protocol and LX200, so SynScan, SkyFi, StarSense, OnStep, INDI/ASCOM bridges).
- Search everything offline: 53k stars, 12.7k deep-sky objects, planets and their moons, asteroids, comets, satellites, by any catalogue name (M 31, NGC 7000, HIP 11767, α UMi…).
Small things
- Time travel with a speed slider, the Moon phase for any date, a Sun warning when you point near it, an ambient soundtrack (off by default), favourites, sharing a snapshot of the sky.
The sky itself is Stellarium Web Engine (the C engine behind stellarium-web.org), compiled to WebAssembly and running fully on the phone. Everything around it is ours.
| Folder | What's in it |
|---|---|
engine/ |
Stellarium Web Engine at upstream commit 15cd08a2, with our patches (60 fps on high-dpi screens, touch cancel, render-loop recovery, WebGL context loss, zstd data files, transparent clear for AR, and a few more). Build with engine/build-wasm.sh (emsdk). |
web/ |
The sky page (TypeScript + Vite): UI, search, Tonight, calendar, alerts, conditions, 3D view (three.js), instruments, telescope. All the app's screens live here so it also runs in a browser. |
app/ |
The iOS app (Expo SDK 57): a full-screen WebView over the sky page, plus native bits a web page can't do well: CoreMotion pointing (modules/star-motion), the telescope TCP client, camera, notifications, haptics, location, sharing. |
data/ |
Bundled offline data: sky packs mirrored from Stellarium's data server, planet maps, NASA models, the ambient track. |
docs/ |
Feature checklist against Stellarium Mobile Plus and the other paid apps. |
# the sky page in a browser (needs the engine built once: engine/build-wasm.sh)
cd web && npm install && npm run dev # http://localhost:5180
# the iOS app
cd app && npm install
./scripts/sync-web.sh # build the sky page into app/sky
npx expo run:iosweb/scripts/fetch-skydata.py re-downloads the offline sky packs into data/skydata. app/scripts/testflight.sh <build> archives and uploads to TestFlight with an App Store Connect API key.
Nothing is collected. No accounts, no analytics, no tracking. Your location stays on the phone, except that a rounded latitude/longitude goes to Open-Meteo for the weather forecast (and to the place search if you search for a place). See the privacy policy.
Issues and pull requests are welcome. If something's wrong in the sky (a planet in the wrong place, a missing star, a wrong rise time), please include your location and the date/time you were looking at.
AGPL-3.0, same as the engine it's built on. Data keeps its own licences, see CREDITS.md.