The free space simulation that lets you explore our universe in three dimensions. Celestia runs on Windows, Linux, and Mac OS X, providing photo-realistic, real-time, three-dimensional viewing of the solar system, the galaxy and the universe. It is an easy to use, freely-distributed, multi-platform, open source, software package which has become a valuable tool for astronomy education.
a complete development utility for graphics of tile-based games. The application contains a bitmap editor for creating tiles and sprites and a map editor for designing level maps.
a Virtual Globe and World Atlas. Marble offers different thematic maps: A classroom-style topographic map, a satellite view, street map, earth at night and temperature and precipitation maps. All maps include a custom map key, so it can also be used as an educational tool for use in class-rooms. For educational purposes you can also change date and time and watch how the starry sky and the twilight zone on the map change.