Comparison

Mars Book vs Project Planet Space

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

Head to head
About

Mars Book

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The Mars Book is an app that is dedicated for observing Mars which will make close approach in summer 2020. Mars will come close to Earth from September 2020 through October 2020. Closest approach will take place on October 6, 2020. Mars Book is a highly useful Mars observing app which will indicate the location of Mars visible in the sky. It shows you why Mars Close Approach will take place, and it is explained readily using animated illustrations and star charts at a viewpoint from outer Space. Mars Close Approaches taking place 23 times from the year 2003 through 2050 will be displayed and apparent retrograde motion of Mars will be displayed. Enjoy Mars Close Approach this summer with the Mars Book app!

About

Project Planet Space

Features
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Project Planet - an interactive map of our solar system How much would you weigh on Jupiter? Why does a day on Mercury last longer than its year? Project Planet turns space facts into a fingertip-sized journey. Scroll through all nine planets (Pluto included), feel each world's pull on your own body, and explore the numbers astronomers have spent decades collecting. Highlights - Sticky scroll across the system: from Mercury to Pluto, each planet stays centred long enough for you to take it in. - You, on every world: enter your weight and age once and watch them recalculated by each planet's gravity and orbital period. - Five rich widgets per planet: surface temperature with reference markers (Antarctica, freezing, boiling), atmospheric pressure with composition chart, travel times from Earth from walking up to the speed of light, gravitational force with everyday objects (phone, backpack, car), and an interactive pressure simulator with phase changes for water, oxygen, CO2, hydrogen, nitrogen and mercury (Antoine equation under the hood). - Six languages: Czech, English, German, Slovak, Spanish and French, auto-detected from your device. - Metric or imperial: switch instantly; weights, temperatures and distances follow your preference. - Crafted to feel like a small cosmic museum: dark cosmic theme, hand-tuned typography, subtle scroll choreography, and a right rail that lets you jump to any planet. - Built on real data: gravitational accelerations, orbital periods, NASA mean temperatures, atmospheric compositions and substance phase transitions. Requires an internet connection. The app runs as a continuously updated webview and uses native iOS capabilities such as haptic feedback to add a tactile dimension to your interstellar journey.

Screenshots

Mars Book3 screens
Project Planet Space4 screens

Verdict

The call

The clearest difference is iOS requirement: Mars Book at 9.0 against Project Planet Space's 15.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Mars Book ships an update every 13 months, Project Planet Space every 25 months. The most recent releases landed on September 10, 2026 and May 16, 2026 respectively.

Scorecard1 real difference ยท 5 level
Mars Book versus Project Planet Space: the parameters behind the verdict, then further details
ParameterMars BookProject Planet Space
PriceFreeFree
Update frequencyEvery 13 months โ€” betterEvery 25 months
AdsNoNo
In-app purchasesNoNo
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS9.0 โ€” better15.0
Further details โ€” not scored
Size14 MB2 MB
Age rating4+4+
DeveloperVixen Co.,Ltd.Miroslav Hanzelka

In-app purchases

None

Mars Book

No in-app purchases

None

Project Planet Space

No in-app purchases

Questions

Is Mars Book free?
Mars Book is free to download, with no in-app purchases.
Is Project Planet Space free?
Project Planet Space is free to download, with no in-app purchases.
Do Mars Book or Project Planet Space have ads?
Neither Mars Book nor Project Planet Space shows ads.
Which is updated more often, Mars Book or Project Planet Space?
Mars Book ships an update every 13 months, and Project Planet Space every 25 months. Most recently, Mars Book was updated on September 10, 2026 and Project Planet Space on May 16, 2026.

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