Cosmology vs Stars Units Sizes Objects
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Cosmology
Explore the universe with stunning high-resolution images of celestial bodies. Journey through space, visiting planets and their moons, while learning about the evolution of space, time, and matter. Ponder the profound mysteries of existence.
- High-resolution images of planets, nebulae, and galaxies
- Interactive space travel to planets and moons
- Learn about the evolution of space, time, and matter
- Expert narration by Dr. Aaron Day
- Exploration of existential mysteries of the universe
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Explore the universe with 100s of high resolution images of planets, nebulae, galaxies, and more. Travel through space, visiting every planet and their major moons. Learn about the creation of space, time, and matter, and their evolution into stars, galaxies, and planets in the present day. Ponder the deep, existential mysteries of the universe. The story of creation is told by Dr. Aaron Day. Dr. Day earned his Ph.D. at the University of California, San Diego for research in cosmology.
Stars Units Sizes Objects
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.
- 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
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Size of the smallest to largest objects and stars. Compare the size of objects in the universe. Object images. Pinch/Zoom image. Pan/Move image. Rotate image. Double tap to reset an image. From the smallest to the largest one. From planck length to observable universe. From Yoctometre, Zeptometre, Attometre, Femtometre, Picometre, Nanometre, Micro, Millimetre, Centimetre, Metre, KiloMetre, Lightyear, Parsecs, Billion Lightyears to 93 Billion Lightyears. Size of objects, particles, atoms, cells, stars and galaxies. Get to know the stars. Get to know the spaces. get to know the universe. How small is this world. How big is the universe. And How great is the creator. How far is the star distance from earth. Two way 18 distance unit conversion. planck length, yoctometer, zeptometer, attometer, femtometer, picometre, nanometre, micrometre, Millimeter, Centimeter, Meter, Kilometer, Inch, Foot, Mile, Astronomical, Lightyear, Parsecs. Perform auto conversion when picker is changed. Share conversion result. Reset unit convertor.
Screenshots
Verdict
The clearest difference is rating: Cosmology at 4.7 against Stars Units Sizes Objects's 4.2. Cosmology also leads on ads (none vs shown) and ratings volume (505 vs 5). On price, in-app purchases, device support and iOS requirement 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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Cosmology holds the better App Store score, 4.7 against 4.2. That said, the two scores are not equally well evidenced: Cosmology has 505 ratings behind it against 5, so its average is the more settled of the two. Written reviews point the same way: 89% of Cosmology's written reviews are positive against 80% of Stars Units Sizes Objects's.
Cosmology ships an update monthly, Stars Units Sizes Objects every 4 months. The most recent releases landed on October 15, 2026 and September 22, 2026 respectively.
| Parameter | Cosmology | Stars Units Sizes Objects |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (505 ratings) — better | 4.2 (5 ratings) |
| Positive reviews | 88.6% of reviews — better | 80.0% of reviews |
| Number of ratings | 505 — better | 5 |
| Update frequency | Monthly — better | Every 4 months |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Free — better | Ad-supported |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 11.0 | 11.0 |
| Further details — not scored | ||
| Size | 190 MB | 124 MB |
| Age rating | 4+ | 4+ |
| Developer | Aaron Day | Mudarmeen Munlin |
Customer experience
Cosmology
Stars Units Sizes Objects
Bugs and requests
Cosmology
Reported bugs
2 issues- Image display interference/hacking concerns
- App feels incomplete in certain sections
Requested features
6 requests- More interactive activities and engagement features
- Text-to-speech functionality
- More detailed explanations for beginner-level users
- Additional sub-categories and content sections
- Regular updates with current astronomical images
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- Alternative cosmological perspectives or viewpoints
Stars Units Sizes Objects
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Cosmology
No in-app purchases
Stars Units Sizes Objects
No in-app purchases
Questions
Is Cosmology free?
Is Stars Units Sizes Objects free?
Which has better reviews, Cosmology or Stars Units Sizes Objects?
Do Cosmology or Stars Units Sizes Objects have ads?
Which is updated more often, Cosmology or Stars Units Sizes Objects?
Other comparisons
