If you run Windows the question as to which free sky mapping software to install is trivial, install Cartes du Ciel. If you run Linux, the question is equally as trivial, use KStars. However, if you run Mac OS X things have traditionally not been so good. I have not found a single good free sky mapping program for OS X. So, instead I have switched my attention to getting either the Linux option or the Windows option working on the Mac.
I had hopped that CrossOver Mac would run Cartes du Ciel but it does not. I tried both V2.7 and the version 3.0 beta but, although both installed, neither worked. 2.7 did run better than 3.0 but failed to render the actual maps so it was still useless! That leaves us with just KStars. This does work on OS X but installing it is not as straightforward as one would hope.
This is not a procedure to start unless you have an afternoon or an evening to spare to baby-sit the process. There is very little you actually have to do but occasionally you'll have to give input. Bear in mind that KStars is part of the Edutainment package for KDE so you are basically going to be downloading and building the guts of KDE on top of KStars, that's no small task
Prerequisites for KStars
Before installing KStars you will need to install Apple's X11 (on the OS X DVD), Fink (including it's GUI Fink Commander) and Apple's XCode developer tools (because we have to build KStars from source). Installing X11 and XCode is easy, installing Fink is a little more involved but there are excellent instructions on the Fink web page so there's no point in my repeating them here.
KStars is currently considered experimental on OS X so you have to tell Fink that you are happy to install 'unstable' packages. To do this launch the FinkCommander app go to the
FinkCommander menu and select
Preferences.... In the new Window that pops up go to the
Fink tab and select the check-box to
use unstable packages. Click
OK. You'll be asked for your password at this stage and then Fink will take a few minutes to update itself and add the unstable packages to it's list of packages.
Now, simply enter
KStars into the search bar in FinkCommander, and it should find the KStars package. Because KStars is still 'unstable' there is no binary version of it available so you have to install from source. Right click the
KStars package and select
Source -> Install. Fink will now go off and get all the packages KStars needs and then KStars itself and then automatically build the lot for you. This may take some time and you may be asked for your password a few times during this process, this is normal on OS X for security reasons. You will also be asked a number of questions, you can accept the default answer on them all except the third one. Lynx does not install correctly (at least on PPC macs) so select links (option 3) instead. Once it starts downloading and compiling you can leave it alone. I generally leave this part running over night because it takes a few hours.
KStars is now installed but don't expect to see an icon for it or anything like that. To run it you have to get your hands dirty in a terminal. To do this start X11 and then in the terminal that opens up enter
/sw/bin/kstars and KStars will start. This is not nice to have to do so I have written a small AppleScript app to launch KStars from the Dock or the Applications folder like a regular app. You can get this launcher on the downloads page on my home page. Just open the DMG and drag and drop the KStars Launcher app into your Applications folder.