Comparison

Encyclopedia vs Stars Units Sizes Objects

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Encyclopedia

Explore the solar system with extensive articles and high-definition images. This app offers comprehensive information, engaging content, and a user-friendly interface, making it suitable for both children and adults interested in space.

Highlights
  • Thousands of articles and HD photos
  • Comprehensive solar system information
  • Engaging and easy-to-understand content
  • Offline availability
  • Badge collection for reading
  • Intuitive user interface
Features
Read full description

Explore 386 illustrated articles about planets, moons, dwarf planets, asteroids, comets, astronomy, missions, discoveries, and the science of our solar system. Search article titles and full text, open clear article pages, and follow linked topics without losing your place. Reading progress and themed badges help you build a path through the collection. Explore the solar system from several angles: - Timeline view follows discoveries, missions, scientists, and changing ideas. - Graph view reveals relationships between worlds, spacecraft, people, and concepts. - Map view adds geographic context for observatories, discoveries, and missions where source material provides it. - References and image credits keep source attribution visible. Thirty articles are free to read. A one-time purchase unlocks the complete encyclopedia for offline reading, including maps, timelines, and graphs. Monthly or annual Premium includes the complete encyclopedia plus AI chat, with a seven-day free trial for eligible new subscribers. People who bought the original Full Version can restore permanent offline encyclopedia access; AI chat remains a separate Premium feature. AI chat answers grounded questions about the solar system and links back to relevant articles so you can continue reading and check the context. Article text is adapted from Wikipedia contributors under Creative Commons Attribution-ShareAlike 4.0. Every article includes source, revision-history, and image-credit links. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

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.

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
Read full description

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

Encyclopedia4 screens
Stars Units Sizes Objects4 screens

Verdict

The call

The clearest difference is in-app purchases: Stars Units Sizes Objects at none against Encyclopedia's 1. Stars Units Sizes Objects also leads on update cadence (every 4 months vs every 62 months) and rating (4.2 vs 3.8). Encyclopedia's advantage is ads (none vs shown). On price, review sentiment, ratings volume and device support 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Encyclopedia sells 1 one-off in-app purchase. Stars Units Sizes Objects asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Stars Units Sizes Objects holds the better App Store score, 4.2 against 3.8. Both are backed by a comparable volume of ratings — 14 and 5 respectively. Written reviews complicate that: 83% of Encyclopedia's written reviews are positive against 80% of Stars Units Sizes Objects's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

Encyclopedia ships an update every 62 months, Stars Units Sizes Objects every 4 months. The most recent releases landed on September 3, 2026 and September 7, 2026 respectively.

Scorecard6 real differences · 4 level
Encyclopedia versus Stars Units Sizes Objects: the parameters behind the verdict, then further details
ParameterEncyclopediaStars Units Sizes Objects
PriceFreeFree
Rating3.8 (14 ratings)4.2 (5 ratings) — better
Positive reviews83.3% of reviews — better80.0% of reviews
Number of ratings14 — better5
Update frequencyEvery 62 monthsEvery 4 months — better
AdsNo — betterYes
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesAd-supported — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.011.0 — better
Further details — not scored
Size322 MB124 MB
Age rating4+4+
DeveloperGood Spider, LLCMudarmeen Munlin

Customer experience

Encyclopedia

All ratings14 ratings
Positive71.4%
Neutral0.0%
Negative28.6%
Written reviews6 reviews
Positive83.3%
Neutral0.0%
Negative16.7%

Stars Units Sizes Objects

All ratings3 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews5 reviews
Positive80.0%
Neutral0.0%
Negative20.0%

In-app purchases

1 purchases

Encyclopedia

One-time1
  • Full Version$2.99
None

Stars Units Sizes Objects

No in-app purchases

Questions

Is Encyclopedia free?
Encyclopedia is free to download, with in-app purchases available.
Is Stars Units Sizes Objects free?
Stars Units Sizes Objects is free to download, with no in-app purchases.
Which has better reviews, Encyclopedia or Stars Units Sizes Objects?
Stars Units Sizes Objects is rated higher. Encyclopedia averages 3.8 out of 5 from 14 ratings, while Stars Units Sizes Objects averages 4.2 from 5 ratings.
Do Encyclopedia or Stars Units Sizes Objects have ads?
Stars Units Sizes Objects shows ads; Encyclopedia does not.
Which is updated more often, Encyclopedia or Stars Units Sizes Objects?
Encyclopedia ships an update every 62 months, and Stars Units Sizes Objects every 4 months. Most recently, Encyclopedia was updated on September 3, 2026 and Stars Units Sizes Objects on September 7, 2026.

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