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.
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!
Project Planet Space
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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
Verdict
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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
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.
| Parameter | Mars Book | Project Planet Space |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 13 months โ better | Every 25 months |
| Ads | No | No |
| In-app purchases | No | No |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 9.0 โ better | 15.0 |
| Further details โ not scored | ||
| Size | 14 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Vixen Co.,Ltd. | Miroslav Hanzelka |
In-app purchases
Mars Book
No in-app purchases
Project Planet Space
No in-app purchases
Questions
Is Mars Book free?
Is Project Planet Space free?
Do Mars Book or Project Planet Space have ads?
Which is updated more often, Mars Book or Project Planet Space?
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