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A Java library for calculation of sun and moon positions and phases.


  • Lightweight, only requires Java 8 or higher, no other dependencies
  • Android compatible, requires API level 26 (Android 8.0 "Oreo") or higher. For older Android versions, use commons-suncalc v2, which is similar to this version, but does not use the Java Date/Time API.
  • Available at Maven Central
  • Extensive unit tests


Astronomical calculations are far more complex than throwing a few numbers into an obscure formula and then getting a fully accurate result. There is always a tradeoff between accuracy and computing time.

This library has its focus on getting acceptable results at low cost, so it can also run on mobile devices, or devices with a low computing power. The results have an accuracy of about a minute, which should be good enough for common applications (like sunrise/sunset timers), but is probably not sufficient for astronomical purposes.

If you are looking for the highest possible accuracy, you are looking for a different library.

Quick Start

This library consists of a few models, all of them are invoked the same way:

ZonedDateTime dateTime = // date, time and timezone of calculation
double lat, lng = // geolocation
SunTimes times = SunTimes.compute()
        .on(dateTime)   // set a date
        .at(lat, lng)   // set a location
        .execute();     // get the results
System.out.println("Sunrise: " + times.getRise());
System.out.println("Sunset: " + times.getSet());

Read the online documentation for examples and API details.

See the migration guide for how to migrate from a previous version.


This library bases on:

  • "Astronomy on the Personal Computer", 4th edition, by Oliver Montenbruck and Thomas Pfleger
  • "Astronomical Algorithms" by Jean Meeus



commons-suncalc is open source software. The source code is distributed under the terms of Apache License 2.0.