Solar System Objects
The ssystem.ini file in the data directory can be extended to contain comets and asteroids. Here are a few extended ssystem.ini files which you can use. If you want just some of the bodies from one file and some from another, you will have to copy and paste the relevant sections of the various files together.
Future versions of Stellarium will contain some sort of method to manage groups of extra bodies, but for now it is manual.
|Hendrik's Comet List||here||2008-02-16||This file contains a lot of the brighter comets.|
|Hendrik's Great Comet List||here||2008-02-17||This file contains a bunch more comets, including multiple fragments of Shoemaker-Levy 9.|
|Selected asteroids||here||2008-02-17 (corrected)||Some bright and/or large asteroids.|
Note that your ssystem.ini file must contain all bodies referenced as parent bodies of objects in your ssystem.ini file - you can't say that the moon is in orbit around Earth, and then not have an Earth body - Stellarium will crash if you do this.