Planetary Clock vs Universe Size Comparison
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Planetary Clock
Visualize the precise positions of all planets in the Solar System for any given day. It uses accurate NASA data for orbital calculations and relative planet sizing, offering a clear, educational view of celestial mechanics.
- Real-time planet positions
- Accurate orbital calculations
- Uses NASA data
- Relative planet sizing
- Educational solar system view
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Planetary Clock is simple and elegant app what shows positions of all planets of the Solar System at any given day. The app uses precise calculation to determine accurate positions in real time. Sun’s and planets sizes are not to scale in order to show them clearly, but other parameters such as size of orbit, eccentricity, shape of the orbit and position of planets are calculated using precise NASA data. Planets are also realistically sized to each other
Universe Size Comparison
Explore the vastness of space and understand celestial body dimensions through interactive 3D comparisons. Discover the scale of planets and stars, from our Sun to hypergiant stars, with guided tours and free comparison modes.
- 3D astronomical comparisons
- Tour Mode with guided explanations
- Free Mode for custom comparisons
- Scale comparisons of planets and stars
- Detailed celestial body information
- Elegant user interface
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Universe Size Comparison is a unique 3D astronomical app that will make you understand the real dimensions of the universe and how small we are. Have you ever wondered how big the Sun is compared to Earth? Or what is the largest planet between Mars and Earth? Do you want to find out the dimensions of some of the most famous stars in the sky like Rigel and Betelgeuse in comparison to our Sun? Do you want to compare everything with the hypergiant star VY Canis Majoris? Universe Size Comparison is the right app for you. The app offers two modes: Tour Mode and Free Mode. Tour mode will guide you on a spectacular journey where you will see planets and stars compared in full scale. All accompanied by simple and clear explanations regardless of the level of knowledge of the subject. The Free mode will allow you to compare two celestial bodies of your choice in scale. You will also find out more information on the bodies you are comparing thanks to an elegant user interface designed to offer the maximum user experience.
Screenshots
Verdict
The clearest difference is rating: Planetary Clock at 4.9 against Universe Size Comparison's 3.1. Planetary Clock also leads on price ($0.99 vs $1.99) and iOS requirement (11.4 vs 13.0). Universe Size Comparison's advantage is update cadence (every 4 months vs every 27 months) and review sentiment (67% vs 57%). On ratings volume, ads, in-app purchases and monetization model 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
Planetary Clock costs $0.99 and Universe Size Comparison $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Planetary Clock holds the better App Store score, 4.9 against 3.1. Both are backed by a comparable volume of ratings — 34 and 29 respectively. Written reviews complicate that: 57% of Planetary Clock's written reviews are positive against 67% of Universe Size Comparison's, so the app with the better star average is not the one people write more warmly about.
Planetary Clock ships an update every 27 months, Universe Size Comparison every 4 months. The most recent releases landed on August 19, 2026 and September 15, 2026 respectively.
| Parameter | Planetary Clock | Universe Size Comparison |
|---|---|---|
| Price | $0.99 — better | $1.99 |
| Rating | 4.9 (34 ratings) — better | 3.1 (29 ratings) |
| Positive reviews | 57.1% of reviews | 66.7% of reviews — better |
| Number of ratings | 34 — better | 29 |
| Update frequency | Every 27 months | Every 4 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod, Apple TV — better |
| Requires iOS | 11.4 — better | 13.0 |
| Further details — not scored | ||
| Size | 14 MB | 411 MB |
| Age rating | 4+ | 4+ |
| Developer | Piotr Knapczyk | Daniele Citi |
Customer experience
Planetary Clock
Universe Size Comparison
In-app purchases
Planetary Clock
No in-app purchases
Universe Size Comparison
No in-app purchases
Questions
Is Planetary Clock free?
Is Universe Size Comparison free?
Which has better reviews, Planetary Clock or Universe Size Comparison?
Do Planetary Clock or Universe Size Comparison have ads?
Which is updated more often, Planetary Clock or Universe Size Comparison?
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