# 认识天文知识 vs Three

The clearest difference is in-app purchases: 认识天文知识 at none against Three's 1. 认识天文知识 also leads on iOS requirement (10.1 vs 16.0). Three's advantage is update cadence (every 4 days vs every 27 months). On price, ads and device support there is nothing between them.

Both are free to download. Three sells 1 one-off in-app purchase. 认识天文知识 asks for nothing beyond the download.

认识天文知识 ships an update every 27 months, Three every 4 days. The most recent releases landed on October 3, 2026 and October 19, 2026 respectively.

## The numbers

| Metric | 认识天文知识 | Three |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/three-body-simulation/id6817179834/reviews)** |
| Number of ratings | — | **1** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 27 months | **Every 4 days** |
| Monetization | — | Free with in-app purchases |
| Size | 33 MB | 6 MB |
| Requires iOS | **10.1** | 16.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [运涛 余](https://appshunter.io/developer/977049266) | [志强 曾](https://appshunter.io/developer/1800987336) |

## What reviewers say

### 认识天文知识

[App page](https://appshunter.io/ios/app/id698569503)

**Features:** macOS Compatibility

**In-app purchases:** none


### Three

[App page](https://appshunter.io/ios/app/three-body-simulation/id6817179834)

Explore the fascinating beauty of gravity and celestial motion. Interact with three bodies, discover countless orbital paths, and experiment with your own gravity scenarios. Turn curiosity into understanding with this educational simulation.

**Highlights:** Explore 16 classic periodic solutions, Discover 10,059 3D periodic orbits, Experiment with custom gravity scenarios, Learn about the three-body problem, Offline exploration of orbits, Interactive celestial motion simulation

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Lifetime Unlock | $0.99 | one-time |


## Frequently asked questions

### Is 认识天文知识 free?

认识天文知识 is free to download, with no in-app purchases.

### Is Three free?

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

### Do 认识天文知识 or Three have ads?

Neither 认识天文知识 nor Three shows ads.

### Which is updated more often, 认识天文知识 or Three?

认识天文知识 ships an update every 27 months, and Three every 4 days. Most recently, 认识天文知识 was updated on October 3, 2026 and Three on October 19, 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.*