Planet Fun is a 4D simulation of the solar system (3D+Time). It shows the Sun, Moon, 9 planets and the star background. The app was developed with Delphi, and runs on multiple platforms.

App open source code (Delphi FMX) is available at:

https://github.com/omarreis/vsop2013

Planet positions are calculated using VSOP2013 and VSOP87. Moon positions use ELP2000. Star background contains 42455 stars of Hipparcos Input Catalogue, with optional constellation lines and names.

Program features:

* Solar system animation with configurable speed
* Choose camera target (Sun, planets, Moon)
* A lighthouse marks the user position on Earth (uses GPS)
* Set date/time between years 1500 and 3000
* Configurable camera distance-to-target
* Touch gestures: one finger pan, two finger zoom and two finger rotation
* Show planet orbits. Each orbit is represented by 52 dots ( For the Earth, it is 1 dot per week)
* Star background, with constellation patterns.
* Actual 3D spheres for the 150 brightest stars.
* Celestial sphere background image, with optional names and constellation lines.
* Solar system heliocentric axis (x and z)
* Activate phone sensor for augmented reality mode. The scene moves to match the real world. Use the [phone] button for that.

Source code and documentation covers many aspects of astronomical algorithms.

video: https://www.tiktok.com/@omar_reis/video/6859411602031119622