Sky Map is the open-source astronomy Android app built for the community.
Check out help.md and troubleshooting.md for accuracy issues and why 'compass calibration' doesn't do what you think it does.
It was originally!
Sky Map has a long history, launching as Google Sky Map on the very first Android phone at Searchology 2009. In 2011 Google ceased active support and the original developers open-sourced it with Google's permission. Google's Open Source Programs Office kindly allowed us to continue to work on it as a personal project, provided we removed Google's branding from it and did not use Google's resources. Today it is still maintained by the same folks. While we no longer work for Google we continue to develop Sky Map using our own resources.
"Stardroid" was the internal name - you can see it's still used as an identifier in the code. Back in the day Google's lawyercats were concerned that 'stardroid' might attract the wrath of, let's say, followers of the Dark Side of the Force so we were strongly encouraged not to call it that. Plus, Google likes to name products after what they are (Photos, Calendar, Docs...). So, Sky Map it is.
Android has evolved significantly since 2009. While most of the code has been rewritten since its Google days, the architecture reflects its origins. We are currently working on a complete modernization of the app. In the meantime, we are continually inspired by the community of users who still find joy in its simplicity and quirks.
I'm glad you asked! We have a section on that below.
Sky Map is a labor of love maintained in our spare time by a couple of ex-Googlers here in Pittsburgh. It is free, open-source, ad-free and we don't track you or sell your data.
If you enjoy using Sky Map, there are several ways to help keep the project alive:
- Donations: Buy Me a Coffee — Every coffee helps keep the servers running and the code flowing!
- Join the beta and give us feedback! Visit the Play Store on your phone.
- Star the Repo: It costs nothing and helps others find the project.
- Contribute: See the Contributing guide or report an issue.
Bug fixes, dependency upgrades, and translations are always welcome. For major changes or new features, please email us first — we may have a different vision and it would be a shame for your work to go to waste.
See CONTRIBUTING.md for full details on build instructions, coding style, and how to submit a PR.
Sigh. I'm sorry we have to do this. But this legalese is to prevent lazy people taking the source code and releasing a clone of Sky Map that is just stuffed full of ads. Yes people do this. It adds no value to the world and just lines their pockets.
The source code of this project is a derivative work of the original open-source Sky Map application (formerly Google Sky Map).
- New Code & Modifications: All new code, modernizations, and modifications authored by Penterakt LLC are licensed under the GNU General Public License v3.0 (GPLv3).
- Legacy Provenance: Portions of the underlying core logic, algorithms, and historical source files remain subject to their original Apache License, Version 2.0. Original copyright headers and notices within inherited files have been preserved as required by the Apache 2.0 terms.
- Combined Work: The project as a combined distribution is compiled and distributed under the terms of the GPLv3. Any third-party forks, modifications, or derivative versions of this combined codebase must be completely open-sourced under the GPLv3.
The open-source code licenses (GPLv3 and Apache 2.0) apply strictly to the functional source code. All proprietary visual artwork, custom UI layouts, onboarding graphics, launcher icons, and designs contained within this repository are Copyright © 2026 Penterakt LLC, All Rights Reserved.
These visual assets are NOT open-source and may not be used, duplicated, or modified in any third-party fork or distribution without express written consent.
(Note: This reservation excludes any public-domain or open-licensed scientific datasets, such as NASA/ESA astronomical imagery or public star catalogs, which remain governed by their original respective terms.)
The app name, project titles, logos, and associated branding elements constitute protected trade names and trademarks of Penterakt LLC.
Subject to the platform terms of the public code hosting service (e.g., GitHub's permission to view and fork repositories on-platform for personal use), you are strictly prohibited from using these trademarks or protected app names in any independent fork, clone, or marketplace distribution. Any independent compilation or distribution of this application published to any app store (such as Google Play, F-Droid, or Amazon Appstore) must be entirely re-branded under a unique identity.
Appropriately, for a star chart app, here's a star chart:
![@gemini-code-assist[bot]](https://avatars.githubusercontent.com/in/956858?s=64&v=4){kind=small}
![@github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=64&v=4){kind=small}
