Celestia vs Never Forget 9
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Celestia
Explore the universe in real-time 3D. Visit planets, moons, star clusters, and galaxies, viewing them from any point in space and time. Customize your experience with expandable content and detailed simulations.
- Real-time 3D space visualization
- Explore planets, moons, stars, galaxies
- Accurate solar system object positions
- Interactive planetarium mode
- Expandable content with add-ons
- Customizable celestial databases
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Celestia — real-time 3D visualization of space 3D Space Simulator | Celestia lets you explore our universe in three dimensions. Celestia simulates many different types of celestial objects. From planets and moons to star clusters and galaxies, you can visit every object in the expandable database and view it from any point in space and time. The position and movement of solar system objects is calculated accurately in real time at any rate desired. Interactive Planetarium | Celestia serves as a planetarium – for an observer on any celestial object. You can easily navigate to any world and land on its surface. When used as a planetarium, Celestia shows accurate positions of solar system objects in the sky. You can switch labels and other supporting features on and off with hotkeys, or zoom in and out on an object of interest, for example Jupiter’s system of moons. Expandable Content | Customize Celestia according to your needs. Celestia’s catalogues can be easily expanded. There are many different add-ons available containing new objects like comets or stars, high-resolution textures of Earth and other well mapped solar system bodies, as well as 3D models for asteroids and spacecraft on precise trajectories. Even fictional objects from well-known sci-fi franchises can be found. EULA(End User License Agreement): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Never Forget 9
This app helps you remember the events of September 11, 2001. It provides facts about the day and sends push notifications to mark the exact times of key historical moments.
- Remember 9/11 events
- Learn facts about the day
- Receive timed push notifications
- Mark key event times
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Remember 9/11 like never before. Remember facts about the day and even get a push notification at the same time the key events happened on September 11, 2001.
Screenshots
Verdict
The clearest difference is in-app purchases: Never Forget 9 at none against Celestia's 4. Never Forget 9 also leads on rating (4.6 vs 4.4). Celestia's advantage is update cadence (fortnightly vs every 10 months). On price, review sentiment, ratings volume and ads 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. Celestia sells 4 in-app purchases, starting at $0.99 per 7 days. Never Forget 9 asks for nothing beyond the download.
Never Forget 9 holds the better App Store score, 4.6 against 4.4. Both are backed by a comparable volume of ratings — 338 and 287 respectively. Written reviews complicate that: 79% of Celestia's written reviews are positive against 74% of Never Forget 9's, so the app with the better star average is not the one people write more warmly about.
Celestia ships an update fortnightly, Never Forget 9 every 10 months. The most recent releases landed on October 27, 2026 and October 22, 2026 respectively.
| Parameter | Celestia | Never Forget 9 |
|---|---|---|
| Price | Free | Free |
| Rating | 4.4 (338 ratings) | 4.6 (287 ratings) — better |
| Positive reviews | 78.9% of reviews — better | 74.1% of reviews |
| Number of ratings | 338 — better | 287 |
| Update frequency | Fortnightly — better | Every 10 months |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad, Mac — better | iPhone, iPod |
| Requires iOS | 16.0 | 15.6 — better |
| Further details — not scored | ||
| Size | 550 MB | 16 MB |
| Age rating | 4+ | 12+ |
| Developer | 林峰 李 | DeerBrain LLC |
Customer experience
Celestia
Never Forget 9
User reviews
Celestia
From 338 App Store ratingsWhat we love
- ⭐ Realistic space simulation
- 🌌 Ability to explore galaxies and star systems
- 🔍 Detailed planet and moon textures
- 📷 Great for taking screenshots
- 🤖 Reminds users of Space Engine
Room to improve
- 🐛 Occasional crashes and glitches
- 🌌 Limited exploration beyond Milky Way and Andromeda
- 🌍 Flat terrain on planets
- 🔍 Lack of detail on some celestial objects
- 🔒 Paywall for some features
Never Forget 9
From 287 App Store ratingsWhat we love
- 👍 Great reminder app
- 👍 Helps remember 9/11
- 👍 Honors lost lives
- 👍 Shows what happened
- 👍 Awesome app
Room to improve
- 🐛 Time is an hour behind
- 🐛 Wrong date displayed
- 🐛 Alarms don't go off
- 🐛 No notifications received
- 🐛 No alert sounds
Bugs and requests
Celestia
Reported bugs
3 issues- Milky Way and other galaxy textures not loading properly
- Crashes when using certain add-ons
- Issues with planet and moon orbits not being accurate
Requested features
5 requests- Add more exoplanets and distant star systems
- Implement terrain generation for planets
- Expand to include more galaxies and the overall universe structure
- Add support for black holes, pulsars, and other exotic objects
- Improve controls and camera movement
Never Forget 9
Reported bugs
8 issues- Time is one hour behind
- Wrong date displayed
- Alarms only go off on September 11
- No alarms went off
- App didn't work
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- Never alerted me
- No alert sounds
- No notification received
Requested features
3 requests- Add video of attacks
- Fix time zone issue
- Add Siren Head next to South Tower
In-app purchases
Celestia
- Celestia PLUS (Weekly)7 Days trial$0.997 Days
- Celestia PLUS (Monthly)$1.991 Month
- Celestia PLUS (Yearly)$19.991 Year
- Celestia PLUS (Lifetime)$79.99
Never Forget 9
No in-app purchases








