CELX scripts can be used to interact with the user, change Celestia's viewpoint and what it shows, and do sophisticated calculations.
CELX first appeared in Celestia v1.3.1. CELX consists of the Lua-programming language combined with a Celestia-specific API. That is, CELX uses Lua syntax and most of the basic Lua-libraries, and adds Celestia-specific functionality.
CELX's biggest advantage over CEL scripting is that it is a real programming language, including control structures like functions and loops, and offers a lot more possibilities, such as interactivity. However this power also makes CELX harder to learn and use, and provides the main disadvantage over CEL scripting.
- CELX Lua Methods: a list of CELX Methods (functions).
A few example Lua scripts for Celestia are available on SourceForge.
A comprehensive list of Celestia's Lua functions is available on Harald Schmidt's Web site.
Some helpful .CEL and .CELX scripts for Celestia are available on Don G's Celestia Scripting Resources