Cosmic Kronos vs Lunar Observer
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Cosmic Kronos
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Natal Charts & Techniques Generate accurate birth charts with multiple house systems (Placidus, Whole Sign, Koch, Equal, Porphyry). Explore essential dignities, asteroids, and both mean and true lunar nodes. Traditional Astrology Profections, Zodiacal Releasing, Firdaria, and Secondary Progressions — classical techniques with modern precision. Live Sky & Transits Track real-time planetary positions, current aspects, Moon phases, retrogrades, and eclipses for any location worldwide.
Lunar Observer
Track the moon's phases, illumination, and rise/set times with precise astronomical calculations. View upcoming solar and lunar eclipses, and access a Hijri calendar. Get optional notifications for celestial events and enjoy an authentic Arabic interface.
- Precise moon phase and illumination tracking
- Sunrise, sunset, moonrise, moonset times
- Upcoming solar and lunar eclipse coverage
- Hijri calendar with moon phase markers
- Customizable notifications for celestial events
- Choice of NASA imagery or 3D terrain model
- Full Arabic localization
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Track the Moon in breathtaking detail. Lunar Observer puts professional-grade astronomical calculations in your pocket — from moonrise and moonset times, illumination percentage, and solar and lunar eclipses, all the way to the Hijri calendar. Everything is computed with absolute precision based on your exact geographic location. PRECISE MOON DATA • Current moon phase with a live readout of illumination percentage and libration. • Sunrise, sunset, moonrise, and moonset times accurate to the second. • Celestial coordinates: altitude, azimuth, and elongation from the Sun. • Distance from Earth, angular diameter, and moon age. 24-HOUR TIMELINE Scrub through the hours with the slider to see exactly where the Moon sits above your horizon at any moment — from the instant it rises to the moment it sets. CHOOSE YOUR MOON Pick between real NASA imagery (per-date photographs from NASA's Scientific Visualization Studio, covering 2022–2026 and updated each new year) — or use a live 3D model built from the actual LRO (Lunar Reconnaissance Orbiter) terrain data, with real libration and earthshine on the dark side (recommended for years not covered by NASA's photos). ECLIPSES Comprehensive coverage of every upcoming solar and lunar eclipse, with local circumstances computed for your coordinates. See whether each event is visible from where you are, along with timings from start to finish, eclipse magnitude, and the Moon's altitude at maximum. HIJRI CALENDAR A monthly view of the Hijri calendar with moon-phase markers, anchored to your local timezone so the Hijri date rolls over correctly no matter where you are in the world. NOTIFICATIONS Optional alerts for tonight's moonrise and moonset, the full moon, the supermoon, solar and lunar eclipses visible from your location, the day-29 Hijri crescent watch, and a daily moon brief at the time you choose. All local on your device, with no notification servers. AUTHENTIC ARABIC INTERFACE Full right-to-left Arabic localization, with an option for Arabic-Indic numerals (٠١٢٣…) or a switch to Western digits, and authentic astronomical terminology — محاق, هلال, بدر, كسوف, خسوف — free from clunky machine translation. Arabic day and month names appear throughout the app. GET STARTED GUIDE A short, friendly walkthrough on first launch that shows you how to navigate the timeline, set your location, explore the Hijri month, and turn on notifications. You can re-open it anytime from the "?" mark in Settings. PRIVACY FIRST Your location data never leaves your device. No tracking, no analytics, no account required. Technical note: the app's calculations are powered by NASA's JPL DE440 ephemeris — the same high-precision model used by NASA Horizons and spacecraft navigation — with the VSOP87 and ELP/MPP02 algorithms as a fallback. Sub-arc-second accuracy, with coverage from 1549 to 2650.
Screenshots
Verdict
The clearest difference is update cadence: Cosmic Kronos at every 8 days against Lunar Observer's every 5 weeks. Cosmic Kronos also leads on iOS requirement (15.1 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Cosmic Kronos ships an update every 8 days, Lunar Observer every 5 weeks. The most recent releases landed on September 15, 2026 and September 1, 2026 respectively.
| Parameter | Cosmic Kronos | Lunar Observer |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (3 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 3 — better |
| Update frequency | Every 8 days — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Free |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.1 — better | 17.0 |
| Further details — not scored | ||
| Size | 102 MB | 329 MB |
| Age rating | 9+ | 4+ |
| Developer | Cheng-Ta Hsieh | Humoud Salmeen |
In-app purchases
Cosmic Kronos
No in-app purchases
Lunar Observer
No in-app purchases

