The premier free planetarium program for Windows is the extraordinary Cartes du Ciel (Sky Charts), written by Swiss astronomer Patrick Chevalley. If you find that none of them are completely suitable, then you can begin exploring the commercial alternatives. We suggest that you try the free alternatives first. But we do think that nearly any amateur astronomer will be completely happy with one or more of the free programs. All of these programs-free and commercial-have their own strengths and weaknesses.

If that were true, no one would ever buy the commercial programs. We won’t say that free planetarium programs are superior to the commercial products in every respect, or even necessarily their equals. Some of the best and most powerful planetarium programs cost nothing. You can pay hundreds of dollars for commercial planetarium software. You can zoom, rotate, and flip charts on-screen to correspond to the view in your finder or telescope, and then print them for use during the observing session. With planetarium software, you can specify the field of view, the level of detail, the types of objects to be plotted, the limiting magnitude, and so on. With printed charts, what you see is what you get. The major advantage of planetarium software relative to printed charts is flexibility. Astronomers use planetarium software at home to plan future sessions, and in the field to provide updated charts of how the sky appears as of that moment and to provide detailed data about the objects they are observing. Unlike static charts, planetarium software can provide a simulation of the night sky as viewed from any specified location, in real time or for some past or future date. Planetarium software is an almost indispensable adjunct to traditional printed charts. Choose the best planetarium software and start planning observing sessions.

Best astronomy software for windows