This is the guide to using the Spelljammer SystemMaker tool. It includes notes, descriptions, and whatever other information I think you might need to use the tool. As users ask questions, I will try to refine this document.

File Menu

Load, Save

These menus allow you to load or save an XML file that describes your system. Examples (using the spheres of the Gatespace cluster) are included in the data directory. Note: the tool maintains only one system in memory at a time.


Generate a random sphere. This uses the random sphere generation tables in the SJ books, with a few additions or modifications where they made sense. Here are a few of the differences (or unimplemented features):

Add Planet

Adds a new random planet to the system. The new planet will have random attributes, and its orbital distance will be greater the current set of planets. If the system has not been created, it will create the first planet as the primary. Once it creates the planet, it will also automatically display the planet editor pane with the new planet's parameters.


This menu brings up a popup pane allowing you to edit properties used by the tool. The current properties are:

View Menu

Full System Map

Generates a map with all planets displayed. The map is to scale.

Inner System Map

Generates a map with only the inner planets displayed The map is to scale.

Outer System Map

Generates a map with only the outer planets (and the primary) displayed. The map is to scale.

Planet Moon Map

Generates a display of a planet-moon system. Not currently working (I'm getting there!).

Sidebar Image

Generates a sidebar images suitable for including on web pages.

Planet Display Panes

Each planet, including the primary, will appear in orbital order in the center of the tool. Each pane will include the basic information about the planet, and whatever descriptive text is available for that planet. Moons initially will not be displayed - hit the Show Moons toggle to view the moons of a planet. To add a moon, hit the Add Moon button; the moon's initial values will be random. Hitting the Edit button will bring up the Planet Edit pane in a popup window.

Planet Edit Pane

The Planet Edit Pane allows you to edit the various values of each planet (and moon, primary, or other astronomical). You can edit the various fields and the description. Once you hit Save, the information will be saved, and the edit pane will close. Reset will reset the information to its current value, and let you keep editing. Note: do not include commas in your text entry.

Image Displays

When the SystemMaker creates an image, it allows you to save the image to a PNG file. Currently PNG is the only format supported. Other formats will be added in the future.

XML Format

You can hand-edit the XML files that the SystemMaker uses to save planetary systems. Some advanced parameters are only editable if you hand-edit the XML file. Look at the examples in the data directory.

The root element is system. The system element can contain one primary node, and as many planet and astronomical nodes as you want. Each of these can contain one or more description elements. Planets can also contain one or more moon elements. Note that XML is case-sensitive.

The system element has two attributes. The first is name, which sets the name of the system. The second optional element is motion. The motion attribute specifies the direction of motion for all planets in the system. Valid values are clockwise, counterclockwise, random (moves at random within an orbit), mixed (planets move either clockwise or counterclockwise), or special (something else weird). I may add other values in the future.

Each of the primary, planet, moon, and astronomical elements has several attributes. Some of these have default values. The attributes, and their descriptions or roles, are the following:

Note: All attribute names are lower-case.