TerraJ is a Java port of fractal terrain and simulated solar system generation programs. The porting has included extensive refactoring, the creation of a documented API to enable reuse of parts in other programs, and extensions such as new Swing user interfaces. Full javadoc for the classes in the project is available.
Frink is a calculating tool and programming language designed to help you in the real world. It tracks units of measurement throughout all calculations and ensures that answers are correct. It converts between systems of measurement, and has a huge library of physical data. It is both a simple calculator for quick calculations and a full-fledged programming language for large tasks. It draws high-quality graphics, handles conversions between time zones, currencies, and historical values of the U.S. dollar and the British pound, translates between several languages, does date/time math, and more.
UFOClock draws an astronomical clock. From it you can read the time of day, phase of the lunar month, ratio of day to night, time until a solstice or equinox, and time until the end or beginning of twilight. The time of day depends on your location on the surface of the Earth, which you can enter on the command line or in a dotfile in your home directory. Location can be given as latitude/longitude or ZIP code. It is called UFO clock because it sort of looks like crop circles. It is based on Sundial by George Williams. It requires GLUT installed to run and the NOVAS library to build.
The Virtual Observatory Quantity Data Model (VOQDM) package is a "thing"-based data model for use with scientific and mathematical data in the International Virtual Observatory (IVO). It is built upon the QML (Quantity Model Language) package and, in general terms, enables fast, convenient serialization/deserialization/manipulation of Quantity-based objects and documents. An important specific application for this package is to enable the I/O of VO-catalog-based data.
WCSLIB is a C library, supplied with a full set of Fortran wrappers, which implements the "World Coordinate System" (WCS) standard in FITS (Flexible Image Transport System). It also includes a PGPLOT-based routine, PGSBOX, for drawing general curvilinear coordinate graticules, and a number of utility programs. The FITS "World Coordinate System" (WCS) convention defines keywords and usage which provide descriptions of astronomical coordinate systems in a FITS image header.
Xgravity is a program for the simulation of 3D gravitational motion of n-bodies. It reads a file with the current state of the bodies, and displays the motion. It features a nice isometric perspective, Red-Green stereographics, and a stereographic perspective which allows you to see the trace in "real" 3D. There is a GTK GUI interface in development, which gives you the ability to perform basic operations with the system, like modifing objects, rotating, eliminating drift, and launching a simulation.
Xplanet was inspired by Xearth, which renders an image of the earth into the X root window. All of the major planets and most satellites can be drawn, similar to JPL's Solar System Simulator. A number of different map projections are also supported, including azimuthal, Mercator, Mollweide, orthographic, and rectangular.
Xplns is a free astronomy simulation software written specifically for Unix. It reproduces real starry sky on your display of X Window System. It calculates the position of many celestial objects accurately. You can enjoy the past and future sky on the desk top as if you have traveled all around the world.