Aciqra is a night sky simulator to show the sky and celestial objects. It uses the highly precise Aloac program to calculate highly accurate positions for planets, stars, comets, and everything else in the sky for thousands of years into the future. It can load a variety of catalogs and even custom ones with a bit of extension.
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.
The FLASH code is a modular, adaptive, parallel simulation code capable of handling general compressible flow problems in astrophysical environments. It has been designed to allow users to configure initial and boundary conditions, change algorithms, and add new physical effects with minimal effort. It uses the PARAMESH library to manage a block-structured adaptive grid, placing resolution elements only where they are needed most. It uses the Message-Passing Interface (MPI) library to achieve portability and scalability on a variety of different message-passing parallel computers.
libnova is a general purpose, double precision, celestial mechanics and astronomical calculation library. It can calculate aberration, nutation, apparent position, dynamical time, Julian day, precession, proper motion, sidereal time, solar coordinates (using VSOP87), coordinate transformations, planetary positions (Mercury - Neptune using VSOP87), planetary magnitude, illuminated disk and phase angle, lunar position (using ELP82), phase angle, elliptic motion of bodies (Asteroid + Comet positional and orbit data), asteroid + comet magnitudes, parabolic motion of bodies (comet positional data), orbit velocities and lengths, atmospheric refraction, rise/set/transit times, and semidiameters of the Sun, Moon, planets, and asteroids.