Orbit simulation designer: instructions

1. Download a sample simulation file.

2. Use any text editor to carefully modify the file.

3. Upload and view your simulation.

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How to edit a simulation XML file

Use any text editor. Here is an example line from a simulation file.


The part you are allowed to edit is shown here in a larger bold font.
The other parts are the start and end tags, do not edit them.

The value between the pX tags specifies the X coordinate of the star or planet's start position.
The value between the vY tags specifies the Y component of the star or planet's start velocity.

Example #1

Download simulation 004.xml. The outer (pink) planet has a non-circular orbit. Can you make its orbit circular?
In your text editor, edit the planet's velocity value between the vY tags. The orbit speed calculator will help decide what velocity to use.

Example #2

To add a 5th planet to simulation 004.xml
In your text editor, highlight and copy the 7 lines which describe the pink planet (including its body start and end tags). Then paste, just above the </system> tag. Change your new planet's position pX value to 5. You can change its color too. And if you want a circular orbit, use the calculator and edit your planet's velocity vY value.

Example #3

Simulation 040.xml is the same as 031.xml but has a special tag called allowAxis added, this will give you a choice of 3 views in the simulator. Also the planet has an extra line added:
This is the Z component of the planet's starting position. Try changing the pZ value to 0.2
This gives the planet a starting position which is not in the same plane as the stars' orbits. It produces an orbit which is tilted relative to the stars' orbits.


The simulator uses a scaleable system of units in which the gravitational constant G = 1.
In these units, a planet of negligible mass, at a distance = 1 from a star of mass = 1, has a circular orbit speed = 1.

Other features

The simulator has a great many more features, and how to use them will be described in a future version of this page.

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