Comparison

Comet Book vs CassiniMIMI

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

Head to head
About

Comet Book

Discover and track comets with this educational app. It provides real-time direction and elevation data to help you locate celestial objects in the night sky. Explore the solar system in 3D and visualize the movement of comets and planets.

Highlights
  • Comet viewing direction and elevation
  • Real-time celestial object tracking
  • 3D Solar System mode
  • Visualize comet and planet motion
  • Observing site guidance
Read full description

The Comet Book app clearly shows when Comets can be viewed and in which direction. The direction and elevation of a Comet can change noticeably in a day due to its fast apparent motion. The moon and a bright planet may be convenient as a guide to find the comet though they have large apparent motion, too. This app determines where Comet is in the sky when it becomes visible at your observing site. You can easily start your observation of a Comet by using Comet Book as a guide to the direction and elevation of the comet. In addition, the new “3D Solar System seen from Space” mode allows you to view the motion of Comets and planets turning around the sun. Please take a look the comet’s movement around our solar system.

About

CassiniMIMI

Explore stunning images and data from NASA's Cassini mission to Saturn. This app provides access to energetic particle data, ENA images, and spectrograms from Saturn's magnetosphere. Discover new scientific releases and browse daily updated plots and movies.

Highlights
  • Energetic charged particle environment study
  • Energetic Neutral Atom (ENA) imaging of Saturn
  • Spectrograms and plots from particle detectors
  • Access to NASA's Planetary Data System (PDS)
  • Daily updated plots and movies
  • Selectable data by source, type, date, and style
Features
Read full description

NASA’s Cassini mission to Saturn has provided a unique opportunity for the Magnetospheric IMaging Instruments (MIMI) to study the energetic charged particle environment, and obtain images of Saturn using Energetic Neutral Atom (ENA) imaging. There is a rich dataset of spectrograms, plots, movies, and images that are now accessible via a dedicated iOS app. Among the data products within the MIMI suite that are viewable through the app, include the ENA images of Saturn taken with the Ion and Neutral CAmera (INCA), and spectrograms and line plots from the Low Energy Magnetospheric Measurement System (LEMMS) and CHarge Energy Mass Spectrometer (CHEMS) particle detectors. The instrument health and safety data are restricted to Cassini team members, while the calibrated science data are available to all. The CassiniMIMI app provides easy access to some of Cassini browse products that are currently in NASA’s publically accessible Planetary Data System (PDS). For some products, the public is now able to see the most up-to-date plots produced on a daily basis. Also, the public now has access to new MIMI data products that are only in the process of being released to PDS. The publically available browse products are selectable by source, type, date, style, plots, and movies. Click on the link below to checkout a description of the public menu selections, highlights of the display, samples of public plots and movies, what’s shown in the icon, and links to supporting links, including the Cassini MIMI website, instrument user’s guide, and archive at PDS.

Screenshots

Comet Book2 screens
CassiniMIMI4 screens

Verdict

The call

Comet Book and CassiniMIMI both sit at 5.0 stars, but that hides the real split: 100% of CassiniMIMI's written reviews are positive against 55% of Comet Book's. CassiniMIMI also leads on update cadence (weekly vs every 6 months) and iOS requirement (8.0 vs 12.0). On price, rating, ratings volume and ads 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 — 5.0 for Comet Book against 5.0 for CassiniMIMI. Both are backed by a comparable volume of ratings — 2 and 2 respectively. Written reviews are what separate them: 55% of Comet Book's written reviews are positive against 100% of CassiniMIMI's.

UpkeepUpdate frequency

Comet Book ships an update every 6 months, CassiniMIMI weekly. The most recent releases landed on October 6, 2026 and October 8, 2026 respectively.

Scorecard3 real differences · 7 level
Comet Book versus CassiniMIMI: the parameters behind the verdict, then further details
ParameterComet BookCassiniMIMI
PriceFreeFree
Rating5.0 (2 ratings)5.0 (2 ratings)
Positive reviews54.9% of reviews100.0% of reviews — better
Number of ratings22
Update frequencyEvery 6 monthsWeekly — better
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.08.0 — better
Further details — not scored
Size10 MB19 MB
Age rating9+4+
DeveloperVixen Co.,Ltd.Johns Hopkins University Applied Physics Laboratory

Customer experience

Comet Book

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews51 reviews
Positive54.9%
Neutral17.6%
Negative27.5%

CassiniMIMI

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Comet Book

No in-app purchases

None

CassiniMIMI

No in-app purchases

Questions

Is Comet Book free?
Comet Book is free to download, with no in-app purchases.
Is CassiniMIMI free?
CassiniMIMI is free to download, with no in-app purchases.
Which has better reviews, Comet Book or CassiniMIMI?
Comet Book and CassiniMIMI are both rated 5.0 out of 5 on the App Store, from 2 and 2 ratings respectively.
Do Comet Book or CassiniMIMI have ads?
Neither Comet Book nor CassiniMIMI shows ads.
Which is updated more often, Comet Book or CassiniMIMI?
Comet Book ships an update every 6 months, and CassiniMIMI weekly. Most recently, Comet Book was updated on October 6, 2026 and CassiniMIMI on October 8, 2026.

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