Give this a try. In your File Manager go to: /usr/share/applications
See if you can find Googleearth in there. If you can't find it by name then perhaps you can recognize the icon. Open the file with your text editor and look for a line: OnlyShowIn=????;
If ???? is, for example GNOME, and you are running MATE then it will not show in the menu. You could edit the file in place, as Root, and remove the line. Even better would be to copy the file to your Home folder to: ~/.local/share/applications and edit it there. That's a hidden folder so make sure you can see them in your File Manager.
Hope this helps.