If you're a big fan of the Solar System and staring into Space through your telescope, then you'll absolutely love OpenUniverse.
Open Universe is an exciting project that brings the Solar System to you - in realtime. Most similar programs simulate or recreate the solar system from static models but this program attempts to show you exactly what is going on at any one time. The program existing in a former state as Solar System Simulator (Ssystem) launched in 1997 and has expanded and advanced so much, that it's now come to encompass the entire universe. The word "Open" has been added to to encourage open source users to improve and enhance the project. This is a million times better than the Space Exploration option on Google Earth with highly detailed images of Earth and the planets. For example, you view the Earth from the Sun, zoom in and out and even zoom in on stars. It labels everything too so no more looking up in the sky and wondering what that constellation is. The graphics are not exactly brilliant - it's a bit block and some of the stars look like blobs of white ink. However as a learning tool, it's a brilliant little resource.
For space exploration fans and those that are trying to teach other about the Universe, OpenUniverse is an exciting and powerful project.