A planetarium software that shows a 3D simulation of the night sky
Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets, nebulae and others things like ground, landscape, atmosphere, etc.
Real time satellite tracking and orbit prediction
Gpredict is a real-time satellite tracking and orbit prediction application. Gpredict can track an unlimited number of satellites and display the data in tables and various graphical view.
Jewish prayer times
Android application that displays list of halachic/halakhic times for Jewish prayers (zmanim and zmanei tefillot).
Java version of Stellarium.