# Smithsonian vs PDF Book Read

The clearest difference is update cadence: PDF Book Read at every 2 weeks against Smithsonian's every 3 months. Smithsonian's advantage is iOS requirement (13.0 vs 26.2). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Smithsonian sells 2 one-off in-app purchases and PDF Book Read sells 2 in-app purchases, starting at $1.99 per year. Whichever you choose, the download price is not the number that matters.

Smithsonian ships an update every 3 months, PDF Book Read every 2 weeks. The most recent releases landed on September 22, 2026 and September 13, 2026 respectively.

## The numbers

| Metric | Smithsonian | PDF Book Read |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 weeks** |
| Monetization | Free with in-app purchases | — |
| Size | 285 MB | 9 MB |
| Requires iOS | **13.0** | 26.2 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [PlayDate Digital](https://appshunter.io/developer/652113715) | [Yuya Takamoto](https://appshunter.io/developer/1881459297) |

## What reviewers say

### Smithsonian

[App page](https://appshunter.io/ios/app/smithsonian-planets/id6504839302)

Explore the solar system with interactive games and animations. Learn fascinating facts about planets, moons, and the asteroid belt. Designed for curious young minds to introduce astronomy basics.

**Highlights:** Fascinating facts about the solar system, Mini games like Space Winter Rush, Interactive activities, Educational animations, Read to Me text, Collect planet badges

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Ads | $1.99 | one-time |
| Buy 5 Planets | $2.99 | one-time |


### PDF Book Read

[App page](https://appshunter.io/ios/app/pdf-book-read/id6760929497)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Annual Premium | $1.99 | per year |
| Lifetime Premium | $2.99 | one-time |


## Frequently asked questions

### Is Smithsonian free?

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

### Is PDF Book Read free?

PDF Book Read is free to download, with in-app purchases available.

### Do Smithsonian or PDF Book Read have ads?

Neither Smithsonian nor PDF Book Read shows ads.

### Which is updated more often, Smithsonian or PDF Book Read?

Smithsonian ships an update every 3 months, and PDF Book Read every 2 weeks. Most recently, Smithsonian was updated on September 22, 2026 and PDF Book Read on September 13, 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.*