There are some really excellent pieces of software available to amateur astronomers ranging in function from presenting the night sky in incredible detail and can even control your telescope (TheSkyX) to image processing (RegiStax). Screen shots and hyperlinks are given below. RegiStax is free to anyone, but to get TheSkyX free, you have to buy a Celestron telescope that bundles it with the hardware (as low as $80 for the PowerSeeker 70AZ - a great deal). Otherwise, the Student edition will cost you $49, Serious Astronomer costs $144, and Professional costs $329. Stellarium is a totally free, open source sky chart program. It appears to do everything TheSkyX does, including interfacing to your telescope for pointing control. TUBA (Touring the Universe through Binoculars Atlas) is a star, plant, and deep sky display tailored to binocular and small telescope users. Originally a for-sale tem, it has been a free download since 2005. Stellaris is another nice, free program for sky charts.
Of course that are also many nice high functionality astronomy apps available for your smartphone and tablet (Apple, Android, Windows). Star Chart is very popular and will use the accelerometer and compass functions to display the night sky view where it is pointed, which is an incredible resource for learning to identify stars, clusters, nebulae, etc. GoSkyWatch is a nice one for the iPad and iPhone.
A Google search free astronomy software will turn up many worthwhile applications.
Posted November 8, 2014