Simulate gravitational interactions between N bodies. Create solar systems, binary stars, and galaxy-scale simulations with trail rendering.
Set up multiple bodies with masses, starting positions, and velocities, then advance simulated time to observe their mutual gravitational motion and rendered trails. The display helps compare orbit shapes, shared motion around a center of mass, close encounters, and ejections. A common surprise is that placing one body beside another does not create a stable orbit by itself. The starting speed and direction must suit the selected masses and separation; even a small mismatch can produce an ellipse, escape trajectory, or very close encounter.
Mass determines each body's gravitational influence, while position and velocity define the starting geometry and momentum. A run represents the evolution of that exact configuration, not a general solution for all similar systems. Reversing one velocity component, changing one mass, or moving a body creates a different problem. For useful comparisons, change one initial value at a time.
Each body attracts the others, with attraction increasing with mass and decreasing rapidly as separation grows. The resulting acceleration changes each body's velocity and position as simulated time advances. A planet therefore moves its star as well as being moved by it, although the heavier body accelerates less. Trails show paths through the displayed coordinate frame; they do not by themselves establish orbital stability.
No. It only shows that the path remained bounded during the displayed interval. Perturbations may accumulate over many revolutions, and a trail that initially repeats can later precess, become chaotic, or end in a close encounter. Test a substantially longer duration and compare runs at finer time resolution before treating apparent stability as meaningful.
Gravity acts mutually, so the planet attracts the star while the star attracts the planet. Both move around their common center of mass. If the star is much heavier, its path is correspondingly smaller and may look like a wobble. A view centered on the star can make that motion less obvious, but it does not remove the underlying interaction.
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