Flat Earth Pro

Review by eFreeware

Flat Earth Pro is for people who follow the moon closely, or who simply enjoy watching how the sky shifts from one evening to the next. It presents the sun, the moon, the earth and four more celestial bodies in a geocentric, flat layout, rendered in real time for whatever date and time you choose. It is a simple, easy-to-use tool for that geocentric view, and the features back the claim up: moon phases, overhead positions, compass directions, altitude and azimuth figures, rise and set times and a lunar events calendar all sit inside one app.

What appeals to me most is the time control. You can rotate the view one way to run time forward and the other way to run it backward, watching the moon's phase change or the sun's position move. You can also jump straight to any date and time and pull the relevant figures for that moment. That combination of a live view and a scrub-able timeline is what separates a sky simulator from a static chart, and it is the part I would reach for first.

It is a paid app at $3.99, with no ads and no in-app purchases. That is a straightforward arrangement: one payment, the whole tool. The install base is modest, over 5,000 downloads, but the 4.8 average across 928 ratings suggests the people who bought it have stayed happy with it. The app has been on Google Play since November 2019 and was last updated in October 2025, so it is not a project that was published and forgotten.

Tracking the moon through its cycle

The moon gets the most attention here. Phases are rendered in real time, and the app calculates lunar perigee and apogee, so you can see when the moon is at its closest and farthest from earth and how that changes its apparent size. There is a dedicated moon size indicator for this, and a lunar events calendar that lists phase and size events with their precise date and time for any year you pick.

Libration and orientation are covered too, which matters if you like to know which part of the moon's surface is tipped toward you on a given night. Put together with the phase rendering, that gives a fairly complete picture of the moon for any moment you care to look up.

The calendar is the part I would expect to use most. Rather than checking the app every evening on the chance that something interesting is happening, you can look ahead and see when the next full moon, new moon or size event falls. Custom notifications at a chosen date and time mean you can set a reminder for the ones you don't want to miss.

Sun, seasons and daylight across the globe

Beyond the moon, the app renders the sun and earth along with four more celestial bodies, and gives overhead positions for all of them at any given moment. Altitude, azimuth and the current zenith position are available for each body, which is the sort of data you want if you are trying to work out where to look in the sky and how high something will be.

The cycle of day and night and the seasons are modeled for any time you select, and there is a daylight coverage visualization that shows which parts of the earth are in sunlight at that instant. Rise and set times are provided for any location on earth, for every body the app covers. That set of features covers the practical questions: when does the sun come up where I am, where is it right now, and how much of the planet is in daylight.

A compass is included, both a local one and directions pointing to the current sky position of each body. If you are standing outside trying to find Venus or the moon, that is more useful than a set of coordinates. A local weather forecast is also part of the package, with a time controller attached, so the forecast can be viewed in step with the rest of the app's timeline.

Setting it up and running it day to day

There is not much of a setup process to describe. Once you start the app, it immediately shows the time, where the sun and moon sit overhead, the current moon phase and more. From there, one touch rotates the view clockwise or counterclockwise to move time forward or backward, or you pick a specific date and time and get the figures for it.

All time zones are built in. That is worth noting for anyone who travels or who wants to check the sky from a location in a different part of the world. The interface is simple and user friendly, and the features are organized around a single view rather than a warren of separate screens.

If you would rather not open the app each time, it can run as a live wallpaper, so the current state of the sky sits on your home screen. You can also save a high-resolution capture to your gallery or share it. The most recent update added a security fix and a developer link in the settings, which is a small but sensible bit of housekeeping.

A geocentric presentation, taken at face value

The app's whole visual premise is a flat, geocentric presentation, and that is what the developer has built. It is not a planetarium that places you at a point on a globe looking outward; it is a different way of arranging the same bodies, with the earth at the center and the sky laid out around it. If you come to it expecting a conventional star map, the framing will be unfamiliar.

What it does offer within that framing is a lot of positional data: overhead positions, altitude, azimuth, zenith, rise and set times, day and night, seasons and daylight coverage. The figures are presented as accurate, and the day-night and seasonal modeling is described as very high accuracy. I would treat those as the developer's claims rather than something to take on faith, but the underlying quantities are the standard ones you would expect from any sky tool.

The scope is deliberately narrow. There is no catalog of stars or galaxies here, and the app does not pretend otherwise. For someone whose interest is the moon and the sun and how they move across a flat sky, that focus is a strength rather than a shortcoming.

Who gets the most from it

I would expect this to suit moon watchers first and foremost. If you follow phases, keep an eye on perigee and apogee, or want a calendar of lunar events with notifications, the app is built around exactly those concerns. The libration and orientation features push it further into the territory of someone who wants the moon rendered properly rather than as a generic disc.

Second, it fits anyone curious about a geocentric view of the sky. The flat presentation is the point of the app, and the time control makes it easy to see how the arrangement changes as you move through days, months and years. That is an educational use as much as a practical one, and it is the sort of thing you can show someone on a phone screen without a long explanation.

It also works for the everyday questions that a sky app answers: when the sun rises and sets where you are, where it is right now, how much of the earth is in daylight, and which way to look to find a particular body. The compass and the weather forecast round those out.

A focused tool for moon and sun watchers

Its strengths are the moon coverage, the time control, the positional data and the lunar events calendar, and it has held a 4.8 average across 928 ratings since it launched in 2019. The feature set is long but coherent, and a recent update shows the app is still being tended to.

The main thing to weigh is the presentation itself. A geocentric, flat layout is a specific way of looking at the sky, and the app is built entirely around it. If that framing appeals to you, or if your interest is mainly the moon and the sun, this is a well-equipped tool at a one-time price. It suits anyone who wants a geocentric flat presentation rather than a conventional planetarium view.

For my part, the combination of real-time rendering, a scrubbable timeline and a calendar of lunar events is a sensible package for anyone who likes to keep track of the moon.

What's new in version 2.2.3

- Security Update. - Add developer link in settings.