Comparison

Celestron SkyPortal vs 星座早見 / Planisphere

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

Head to head
About

Celestron SkyPortal

Explore the cosmos with a comprehensive astronomy suite. Discover stars, planets, and celestial events, and enhance your stargazing with detailed information and audio narration. Connect to compatible telescopes for automatic object location.

Highlights
  • Explore 120,000 stars and celestial objects
  • Simulate night sky past/future
  • Real-time sky synchronization
  • Control compatible WiFi telescopes
  • Animate celestial events
  • Audio narration and object descriptions
  • Night Vision mode
Features
Read full description

Celestron’s newest planetarium app is an astronomy suite that redefines how you experience the night sky. Explore the Solar System, 120,000 stars, over 200 star clusters, nebulae, galaxies, and dozens of asteroids, comets, and satellites—including the ISS. SkyPortal includes everything you need to experience the night sky in an exciting new way. When connected to a compatible Celestron WiFi telescope, you can automatically point the telescope to any object in the database and view it with great detail. Planetarium Features Simulate the night sky and plan your observing session with a custom list of tonight’s best objects based on your exact time and location. Look ahead to see when Jupiter’s Great Red Spot will be visible, animate transits, eclipses, and other celestial events. View hundreds of photos or listen to more than four hours of audio narration to enhance your stargazing experience. •Simulate the night sky from anywhere on planet Earth, up to 100 years in the past or future. •Compass Mode (with compatible devices): Hold your device up to the sky for a real-time synchronized display of celestial objects – from star names, constellations, planets, to nebulae and galaxies. •Control compatible Celestron WiFi telescopes with sophisticated mount modeling for quick and accurate go-to alignment. •Animate transits, conjunctions, eclipses, and other events with SkyPortal's Time controls. •Explore the sky with Night Vision turned on, and preserve your eyesight after dark. •Learn the history, mythology, and science of the heavens with SkyPortal's hundreds of object descriptions. •Browse hundreds of astronomical photographs and NASA spacecraft images •Access over 4 hours of audio commentary to guide you through the best celestial objects. Computerized Telescope Control Pair your device to your compatible Celestron WiFi telescope, align with Celestron’s patented SkyAlign™ technology, and you’re ready to explore! Identify objects instantly. Tap any object and your telescope automatically centers it in the eyepiece. SkyPortal’s telescope alignment incorporates advanced mount modeling, providing better pointing accuracy than other telescope systems which rely on a dedicated computer.

About

星座早見 / Planisphere

This app simulates the night sky, displaying stars, planets, and the moon. It functions like a traditional planisphere but with added digital features, allowing users to easily view celestial positions and predict sunrise/sunset times.

Highlights
  • Real-time sky display
  • Planet and moon tracking
  • Interactive sky map
  • Sunrise/sunset prediction
  • Zoomable interface
  • Dark-friendly screen
Read full description

The planetarium curators of Nagoya City Science Museum have originally designed the Planisphere app. Many people know how to use the planisphere, because we learn it at elementary school. This is the planisphere of the era of IT which added the advantage as an app, with the plain usage of the planisphere printed on paper and plastic. Please look up at the real starry sky with this Planisphere app. The Planisphere app shows the sky of the current time at the start-up. To check the sky at other time, you drag around the date scale with your fingertips to set the date and time. You can use pinch gestures to manipulate a map of the sky. It attends you to enjoy the star watching by glowing in dark place. It is the exceptional planisphere app, because it’s displayed up to the planet positions of the night that is impossible with the printed planisphere! 【Features of the Planisphere application】 ・ Anytime, anywhere: When you look up at the night sky, it stands by in your smartphone or tablet. ・ Very easy usage: The usage of planisphere is exactry same as you learned. Just touch and rotate the board. ・ Quick access : The Planisphere shows the night sky when you start the app. It is easier than a printed planisphere. ・ Prominent planets: The planets always stand out in the night sky. However, the planet positions change day by day, so it is not possible to display on the printed planisphere. The Planisphere app calculates the positions in the night of the 5 planets and the Moon that are seen by the naked eye and displays them as icons on the board. ・ Good at dark places : When we look up at the starry sky, we are of course in a dark place. We needed a torch when using a printed planisphere. But the Planisphere app can be used in the darkness because of the screen light. A tip when using the app is to reduce the screen brightness not to be dazzling. ・ Friendly to any ages: It is difficult to see small letters in a dark place. You can freely zoom in and out with the fingertips on the Planisphere app. Furthermore, it is easier to see than a printed planisphere, since the screen of smart phone or tablet have a light. ・ Sunrise and sunset : You can find the sunrise time by setting a target object to the eastern horizon and the sunset time by setting it to the western horizon on the board. On the Planisphere app, you can find the rough time and direction of sunrise or sunset, because it shows not only stars but also the planets and the Moon. ・ For education : In schools, science museums, planetariums and public astronomical observatories, there are occasions that to explain how to use a planisphere. It is small letters and hard to show to people when explaining the usage. For now, you can connect a smart phone or a tablet to a projector or a big monitor to make the planisphere image larger. There is also a more sophisticated computer version (for Windows and Macintosh) of the Planisphere app. If your school provides tablets to the students, you can use the Planisphere app instead of a printed planisphere. ・ Planetarium of Nagoya City Science Museum opened in 1962. It is the planisphere which contains a lot of curator's experience and know-how. We have made it as an application that we use printed planispheres for the citizen observation party, educational programs, astronomical exhibition room of Nagoya City Science Museum and sell at the museum shop. Bright famous stars, Moon and planets are visible even in the town. Please look up at the real starry sky with this Planisphere app. ・ Astronomical information of Nagoya City Science Museum introduces various astronomical phenomena and events. Please also click here if you would like to know more about the Planisphere app. >Astronomical information http://www.ncsm.city.nagoya.jp/study/astro/ >Planisphere http://www.ncsm.city.nagoya.jp/study/astro/hayami.html

Screenshots

Celestron SkyPortal4 screens
星座早見 / Planisphere4 screens

Verdict

The call

The clearest difference is rating: Celestron SkyPortal at 3.6 against 星座早見 / Planisphere's 1.0. Celestron SkyPortal also leads on review sentiment (32% vs 0%) and ratings volume (354 vs 1). 星座早見 / Planisphere's advantage is update cadence (every 5 weeks vs every 3 months) and iOS requirement (15.0 vs 18.6). On price, 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

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

Celestron SkyPortal holds the better App Store score, 3.6 against 1.0. That said, the two scores are not equally well evidenced: Celestron SkyPortal has 354 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 32% of Celestron SkyPortal's written reviews are positive against 0% of 星座早見 / Planisphere's.

UpkeepUpdate frequency

Celestron SkyPortal ships an update every 3 months, 星座早見 / Planisphere every 5 weeks. The most recent releases landed on November 1, 2026 and November 6, 2026 respectively.

Scorecard5 real differences · 5 level
Celestron SkyPortal versus 星座早見 / Planisphere: the parameters behind the verdict, then further details
ParameterCelestron SkyPortal星座早見 / Planisphere
PriceFreeFree
Rating3.6 (354 ratings) — better1.0 (1 ratings)
Positive reviews31.9% of reviews — better0.0% of reviews
Number of ratings354 — better1
Update frequencyEvery 3 monthsEvery 5 weeks — better
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS18.615.0 — better
Further details — not scored
Size709 MB277 MB
Age rating4+4+
DeveloperCelestron, LLCIMAGE FACTORY CO., LTD.

Customer experience

Celestron SkyPortal

All ratings354 ratings
Positive62.7%
Neutral11.9%
Negative25.4%
Written reviews188 reviews
Positive31.9%
Neutral17.0%
Negative51.1%

星座早見 / Planisphere

All ratings1 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews1 reviews
Positive0.0%
Neutral0.0%
Negative100.0%

Bugs and requests

Celestron SkyPortal

Reported bugs

6 issues
  • Fails to align telescope
  • Telescope points in wrong direction
  • Disconnects frequently
  • Doesn't show deep sky objects
  • Crashes on startup
Show 1 more
  • Incompatible with iOS 14

Requested features

7 requests
  • Add red night mode
  • Improve focus motor control
  • Integrate weather data
  • Provide RA/DEC coordinates
  • Add more celestial objects
Show 2 more
  • Improve video streaming
  • Enhance user interface

星座早見 / Planisphere

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

Celestron SkyPortal

No in-app purchases

None

星座早見 / Planisphere

No in-app purchases

Questions

Is Celestron SkyPortal free?
Celestron SkyPortal is free to download, with no in-app purchases.
Is 星座早見 / Planisphere free?
星座早見 / Planisphere is free to download, with no in-app purchases.
Which has better reviews, Celestron SkyPortal or 星座早見 / Planisphere?
Celestron SkyPortal is rated higher. Celestron SkyPortal averages 3.6 out of 5 from 354 ratings, while 星座早見 / Planisphere averages 1.0 from 1 ratings.
Do Celestron SkyPortal or 星座早見 / Planisphere have ads?
Neither Celestron SkyPortal nor 星座早見 / Planisphere shows ads.
Which is updated more often, Celestron SkyPortal or 星座早見 / Planisphere?
Celestron SkyPortal ships an update every 3 months, and 星座早見 / Planisphere every 5 weeks. Most recently, Celestron SkyPortal was updated on November 1, 2026 and 星座早見 / Planisphere on November 6, 2026.

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