# e vs Celestia

The clearest difference is rating: e at 5.0 against Celestia's 4.4. e also leads on in-app purchases (none vs 4) and review sentiment (90% vs 79%). Celestia's advantage is update cadence (fortnightly vs every 11 months) and ratings volume (337 vs 1). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. Celestia sells 4 in-app purchases, starting at $0.99 per 7 days. e asks for nothing beyond the download.

e holds the better App Store score, 5.0 against 4.4. That said, the two scores are not equally well evidenced: Celestia has 337 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 90% of e's written reviews are positive against 79% of Celestia's.

e ships an update every 11 months, Celestia fortnightly. The most recent releases landed on October 5, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | e | Celestia |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/e-spacetime-converter/id291317973/reviews)** | [4.4 (337 ratings)](https://appshunter.io/ios/app/celestia-space-simulator/id1500434829/reviews) |
| Number of ratings | 1 | **337** |
| Positive reviews | **90.0% of reviews** | 78.9% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 11 months | **Fortnightly** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 4 MB | 550 MB |
| Requires iOS | **15.5** | 16.0 |
| Devices | iPhone, iPod | **iPhone, iPad, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Elliptics, Ltd.](https://appshunter.io/developer/289108972) | [林峰 李](https://appshunter.io/developer/1186547508) |

## What reviewers say

### e

[App page](https://appshunter.io/ios/app/e-spacetime-converter/id291317973)

Explore the universe of spacetime by converting lengths into time and vice versa. This unique calculator uses geometrized units to help you think about the world in new ways and amuse your friends. It's a fun tool for science enthusiasts and students alike.

**Highlights:** Convert length to time, Convert time to length, Geometrized units (c=1), Avoids scientific notation, Supports various input units, Educational and entertaining

**In-app purchases:** none


### Celestia

[App page](https://appshunter.io/ios/app/celestia-space-simulator/id1500434829)

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.

**Highlights:** 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

**Features:** Game Controller support, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Celestia PLUS (Weekly) | $0.99 | per 7 days |
| Celestia PLUS (Monthly) | $1.99 | per month |
| Celestia PLUS (Yearly) | $19.99 | per year |
| Celestia PLUS (Lifetime) | $79.99 | one-time |

**What reviewers like**

- ⭐ Realistic space simulation
- 🌌 Ability to explore galaxies and star systems
- 🔍 Detailed planet and moon textures
- 📷 Great for taking screenshots
- 🤖 Reminds users of Space Engine

**What reviewers complain about**

- 🐛 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

**Reported bugs**

- 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**

- 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


## Frequently asked questions

### Is e free?

e is free to download, with no in-app purchases.

### Is Celestia free?

Celestia is free to download, with in-app purchases available.

### Which has better reviews, e or Celestia?

e is rated higher. e averages 5.0 out of 5 from 1 ratings, while Celestia averages 4.4 from 337 ratings.

### Do e or Celestia have ads?

Neither e nor Celestia shows ads.

### Which is updated more often, e or Celestia?

e ships an update every 11 months, and Celestia fortnightly. Most recently, e was updated on October 5, 2026 and Celestia on October 20, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*