Comparison

KeckWatch 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

KeckWatch

Explore the cosmos with detailed information on stars, planets, galaxies, and nebulae. Discover celestial objects using your device's compass and GPS, and stay updated with news from the W. M. Keck Observatory. Features a night-vision-friendly red interface and offline access.

Highlights
  • Offline celestial exploration
  • Real-time telescope status
  • Compass and GPS integration
  • Detailed object information
  • Hawaiian star names
  • Night vision red interface
  • Keck Observatory news
Features
Read full description

KeckWatch is brought to you by W. M. Keck Observatory, which operates the two largest optical/infrared telescopes on Earth from nearly 14,000 feet on Maunakea in Hawaii. Since first science in 1993 they have become the two most scientifically productive telescopes on Earth. With KeckWatch, you can share in their discoveries. Sporting thousands of stars, all 8 (sorry, Pluto) planets, galaxies, nebula and star clusters, along with status updates and news from Keck Observatory you’ll learn where Orion might be, or what planet was shimmering above the house last night. Features include: •No Internet required. Just a sense of wonder. •Up to date Keck news •See the current status of each telescope, what instruments are in use and what organization is booked for that evening’s observing •See where each scope is currently aimed. •Stars are shown with both standard and traditional Hawaiian names •Zoom in on the planets, see Jupiter and her moons or the rings of Saturn. •See where other users with Beacons. •Compass aware, just aim and gaze. •Thousands of pinpoint stars scintillating like diamond dust in the palm of your hand •Realistic ghostly band of the Milky Way •Stories behind each constellation •Viewpoint Lock keeps any planet centered •Galaxies, nebula and star clusters •Hubble Space Telescope images •All 8 planets (Pluto is optional) •GPS aware •Red interface to preserve your night vision •What's Up? Gives a quick one snapshot overview of where all of the important stuff is •Touching the sky to reveal hidden data for each object •Planetary data and information

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

KeckWatch4 screens
Stars Units Sizes Objects4 screens

Verdict

The call

The clearest difference is ads: KeckWatch at none against Stars Units Sizes Objects's shown. KeckWatch also leads on update cadence (every 5 weeks vs every 4 months) and monetization model (free vs ad-supported). On price, rating, review sentiment and ratings volume 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. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 4.3 for KeckWatch against 4.3 for Stars Units Sizes Objects. Both are backed by a comparable volume of ratings — 9 and 6 respectively. Written reviews are what separate them: 83% of KeckWatch's written reviews are positive against 80% of Stars Units Sizes Objects's.

UpkeepUpdate frequency

KeckWatch ships an update every 5 weeks, Stars Units Sizes Objects every 4 months. Both last shipped on October 24, 2026.

Scorecard4 real differences · 6 level
KeckWatch versus Stars Units Sizes Objects: the parameters behind the verdict, then further details
ParameterKeckWatchStars Units Sizes Objects
PriceFreeFree
Rating4.3 (9 ratings)4.3 (6 ratings)
Positive reviews83.3% of reviews — better80.0% of reviews
Number of ratings9 — better6
Update frequencyEvery 5 weeks — betterEvery 4 months
AdsNo — betterYes
In-app purchasesNoNo
MonetizationFree — betterAd-supported
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS7.1 — better11.0
Further details — not scored
Size147 MB124 MB
Age rating4+4+
DeveloperMike SmithwickMudarmeen Munlin

Customer experience

KeckWatch

All ratings9 ratings
Positive77.8%
Neutral0.0%
Negative22.2%
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

None

KeckWatch

No in-app purchases

None

Stars Units Sizes Objects

No in-app purchases

Questions

Is KeckWatch free?
KeckWatch 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, KeckWatch or Stars Units Sizes Objects?
KeckWatch and Stars Units Sizes Objects are both rated 4.3 out of 5 on the App Store, from 9 and 6 ratings respectively.
Do KeckWatch or Stars Units Sizes Objects have ads?
Stars Units Sizes Objects shows ads; KeckWatch does not.
Which is updated more often, KeckWatch or Stars Units Sizes Objects?
KeckWatch ships an update every 5 weeks, and Stars Units Sizes Objects every 4 months. Most recently, KeckWatch was updated on October 24, 2026 and Stars Units Sizes Objects on October 24, 2026.

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