This free open-source planetarium software is quite simply stunning. The latest version 0.9.1 came out in January 2008. Previously I had been using Redshift 5, but while trying to locate comets to photograph I was finding the RA and DEC data to be rather inaccurate. The other major limitation of Redshift 5 is that the maximum star magnitude that can be displayed is 14 which often made the verification of photographed comet locations very difficult given that the images usually resolve 15th-16th mag stars.
Having found Cartes du Ciel (also free) to be equally limited in star magnitude unless you download some immense catalogue files I turned to Stellarium and had another look at the downloads available for the programme. To my surprise there were star catalogues (J2000) up to mag 18 readily available in handy compressed files that are just dropped into the main data folder and off you go! As a bonus I also found that bright comet and asteroid data was now available plus some new nebula/galaxy photo textures. With star catalogues loaded up to mag 16 there is no impact on system memory (I have 2Gigs RAM) and some people have reported that the 18 mag catalogue can be used with just 512mb RAM and no obvious system impact! All in all this is shaping up to be one of the best pieces of planetarium software available.
Stellarium oozes quality from the moment you start it up and the startup time takes just 5 seconds now! The night sky looks very realistic and the stars scintillate gently on a black or slightly moonlit background. The foreground is photoreal landscape and can actually be adapted with panorama stitch software to show your own location. There is even an option for some realistic frosty fog at ground level! The controls are all simple to use and the slewing motion to the object of your choice is very smooth and professional. Finding Messier and NGC objects is a breeze with the efficient indexed search function. Nebulae, galaxies and planets have photograph based textures and look superb. All the usual constellation and grid functions are available as well as GoTo control for telescopes via the ASCOM drivers.
Stellarium has now become my first port of call if I want to see what is in the night sky at my location on any given night and build a program of objects to image or observe. If you want to try Stellarium for yourself download it here http://www.stellarium.org/ You will find the Stellarium Wiki here http://www.stellarium.org/wiki/index.php/Main_Page and the Stellarium Forums are here http://sourceforge.net/forum/forum.php?forum_id=278769