planets1
Gravitational simulation of planetary bodies
Overview
Planets is a simple interactive program for playing with simulations of planetary systems. It is great teaching tool for understanding how gravitation works on a planetary level.
The user interface is aimed at being simple enough for a fairly young kid can get some joy of it. There's also a special kid-mode aimed at very young children which grabs the focus and converts key banging into lots of random planets.
Keybindings
Universe definition
a
|
Add Planet |
|---|---|
j
|
Place random orbital planet |
r
|
Place random planet |
u
|
Undo (undoes last planet insertion) |
e
|
Reset to empty universe |
g
|
Go Back (goes back to just after last planet insertion) |
Mouse
|
Click on a planet to delete it |
Physics
- b
-
Toggle bounce (experimental)
Display control
Cursor keys
|
Panning |
|---|---|
c, Space
|
Move display to center of mass |
x
|
Initiate center of mass tracking |
=
|
Zoom in |
-
|
Zoom out |
p
|
Toggle Pause |
o
|
Change all colors randomly |
t
|
Toggle Trace |
d
|
Double Trace Length |
h
|
Halve Trace Length |
Mouse
|
Drag a box around a set of planets to follow the center of mass of those planets |
Program control
- H
-
Display help dialog
- k
-
Display option dialog
- Ctrl-Shift-k
-
Toggle kid-mode. Kid mode locks the keyboard and mouse, so the only way to get out is to toggle kid-mode again to get out.
- l
-
Load Universe After pressing l, press any other character to load the universe with that name. Universes are stored in ~/.planets/ .
- s
-
Save Universe After pressing s, press any other character to save the universe with that name. Universes are saved in ~/.planets/ .
- q, Esc
-
Quit
Technical details
Planets uses a fourth-order runge-kutta approximation for the simulation itself. Planet bouncing is achieved by adding a repulsive force to planets at close quarters. Planets is fairly flexible: you can change the gravitational constant, the time-slice of the simulation, and even the exponent used in the gravitational law. Universes are saved in the ~/.planets directory, and are simple human readable and editable files.
Releases
Unchanged in 11 releases since Debian 3.1 (Sarge).