planets
World Wide Telescope: turn your computer into a planetarium
Offered free by Microsoft, this web-based software acts as a "virtual telescope" letting you and your homeschol students explore the night sky, and the planets. The interface was not immediately intuitive to me, and so I'd recommend you begin with a tour (click on the "tour" option on the menu along the top of the screen.) You can also use the lesson plan provided here: http://www.microsoft.com/education/lessonplans/explorethestars.mspx
