NSim is a simulator of the Solar system, or in general any system of objects with gravitational forces between them. It can visualize the results in a 3D animation, or provide the raw data on the command line. Instead of using pre-computed data like Stelarium or Celestia do, it does the computation itself and thus it's possible to create arbitrary systems of celestial bodies.
The simulator predicts the motions of objects using numerical integration, since there is no analytic solution to a system with more than two bodies. Gravitational interactions are computed with classical Newtonian mechanics and the bodies are modelled as simple point masses (their volume and shape are not taken into consideration).
$ bin/nsim-cmd -f examples/earth-moon-sun.xml
# time Sun_x Sun_y Sun_z Earth_x Earth_y Earth_z Moon_x Moon_y Moon_z
0 0 0 0 128079368.922767 -80628651.5813115 -3492.12286324799 127792152.883098 -80865704.0944675 9563.00363019109
200 0 0 0 128082444.421441 -80623629.9416063 -3492.07035570603 127795365.928979 -80860840.702465 9580.24818598272
400 0 0 0 128085519.722891 -80618608.179338 -3492.01779332642 127798578.867124 -80855977.1132846 9597.48870185548
...
You will need:
-
a compiler that supports C++11 (g++ is recommended)
$ apt-get install g++ -
at least Qt 5.4
-
OpenGL 3.1 (lower versions might work, but are untested)
Afterwards, run:
$ qmake
$ make
Execute:
$ bin/nsim # GUI
$ bin/nsim-cmd -h
Warning: The GUI is in an alpha stage of development, some of the elements might not be implemented yet.
Load a project (a file containing the positions of objects) from the example/
directory and hit the play button to start the animation.
Depending on the algorithm, number of the objects in the simulation and your hardware, the animation might be very slow.