Translation using gettext
If you speak a non-english language, please considere contributing to the developement of Stellarium! It is quite easy :
From version 0.8.0, stellarium fully supports translation into other languages. The translation is performed using gettext. All the strings used in the program are translated and saved in special .po files. These .po file can be edited using a text editor or special program such as Kbabel. An easier way (but less efficient) is to use the Rosetta facility which allow to translate Stellarium online.
Once your .po file is ready, you can compile it into a ".mo" file and test it in the program to check that everything is correct. For example, if you are french and work on "fr.po", save your compiled file "fr.mo" as "stellarium.mo" and copy it into the directory "..../stellarium/data/locale/fr/LC_MESSAGES/".
Re-run stellarium and there you are! Don't forget to remain synchronized with the version of your .po file on Rosetta otherwise you may destroy other's people work. To keep in sync, alway restart to work from the last online version of the .po file, and always upload your modifs when you stop working on it.
POedit po-file editor for Linux and Windows.
KBabel po-file editor for KDE environments