# Open Planetarium — Lightweight planetarium app

> Lightweight planetarium app (iPhone/iPad app by CatsAI Agency.)

- Source: https://appshunter.io/ios/app/open-planetarium/id6799616519 (this page in markdown: same URL + `.md`)
- Developer: [CatsAI Agency](https://appshunter.io/developer/6799471013)
- Category: Education, Reference
- Price: Free
- Age rating: 4+
- Requires: iOS 13.0 · 26 MB
- Languages: American English
- Released: 2026-08-18
- Data updated: 2026-08-18
- User reviews in markdown: https://appshunter.io/ios/app/open-planetarium/id6799616519/reviews.md

## What is Open Planetarium?

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.


## Version history (last 1 release)

### 0.2.0 — 2026-08-18

No release notes.

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-18.*