All you astronomy types can't have all the fun, this is a great utility for us boaters who do night cruising. Having the whole screen go "Red Screen" so you don't lose your night vision is great, while using a navigational program. Have told all my boating friends about it and we all agree there's no better program out there. Even some very expensive navigation programs only dim the screen, still to bright. I highly recommend this great little utility to both Mac and PC users who do any night navigational cruising.