# SOS Explorer vs Stars Units Sizes Objects

The clearest difference is rating: SOS Explorer at 4.7 against Stars Units Sizes Objects's 4.2. SOS Explorer also leads on ads (none vs shown) and monetization model (free vs ad-supported). Stars Units Sizes Objects's advantage is update cadence (every 4 months vs every 11 months). On price, review sentiment, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

SOS Explorer holds the better App Store score, 4.7 against 4.2. Both are backed by a comparable volume of ratings — 20 and 5 respectively. Written reviews point the same way: 86% of SOS Explorer's written reviews are positive against 80% of Stars Units Sizes Objects's.

SOS Explorer ships an update every 11 months, Stars Units Sizes Objects every 4 months. The most recent releases landed on October 9, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | SOS Explorer | Stars Units Sizes Objects |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (20 ratings)](https://appshunter.io/ios/app/sos-explorer/id1358724422/reviews)** | [4.2 (5 ratings)](https://appshunter.io/ios/app/stars-units-sizes-objects/id1576148571/reviews) |
| Number of ratings | **20** | 5 |
| Positive reviews | **85.7% of reviews** | 80.0% of reviews |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 11 months | **Every 4 months** |
| Monetization | **Free** | Ad-supported |
| Size | 249 MB | 124 MB |
| Requires iOS | 12.0 | **11.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [University of Colorado Boulder](https://appshunter.io/developer/972210292) | [Mudarmeen Munlin](https://appshunter.io/developer/1348165664) |

## What reviewers say

### SOS Explorer

[App page](https://appshunter.io/ios/app/sos-explorer/id1358724422)

Explore interactive animated datasets of Earth and space phenomena, from planetary rings to climate change models. This app brings complex environmental processes to life in an intuitive and captivating way, making learning accessible anywhere.

**Highlights:** Streaming high-resolution datasets, Educational videos, User-guided tours, Analysis tools, 100+ datasets, Global and flat map views

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

**In-app purchases:** none


### Stars Units Sizes Objects

[App page](https://appshunter.io/ios/app/stars-units-sizes-objects/id1576148571)

Explore the vastness of the universe, from the smallest particles to the largest cosmic structures. Compare object sizes, view detailed images, and perform unit conversions across a wide range of astronomical scales. Learn about stars, galaxies, and the incredible distances between them.

**Highlights:** Compare object sizes, View object images, Pinch/Zoom and Pan images, Unit conversion for distances, Explore scales from Planck length to observable universe, Learn about stars and galaxies

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is SOS Explorer free?

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

### Is Stars Units Sizes Objects free?

Stars Units Sizes Objects is free to download, with no in-app purchases.

### Which has better reviews, SOS Explorer or Stars Units Sizes Objects?

SOS Explorer is rated higher. SOS Explorer averages 4.7 out of 5 from 20 ratings, while Stars Units Sizes Objects averages 4.2 from 5 ratings.

### Do SOS Explorer or Stars Units Sizes Objects have ads?

Stars Units Sizes Objects shows ads; SOS Explorer does not.

### Which is updated more often, SOS Explorer or Stars Units Sizes Objects?

SOS Explorer ships an update every 11 months, and Stars Units Sizes Objects every 4 months. Most recently, SOS Explorer was updated on October 9, 2026 and Stars Units Sizes Objects on September 22, 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.*