If the recent series of space shuttle missions has piqued or renewed your interest in space, you'll need some astronomy software to help you navigate the skies from your backyard. There are several terrific open source applications available for users of all levels of experience, from casual and novice users to astronomy buffs with a secret desire to become an astronaut.

Here are my four favorite apps to help you find your way around the skies and stars:

Space Shuttle Atlantis launched today on its way to the final Hubble telescope repair mission. There's an old joke originally quipped by astronaut Wally Schirra that NASA spacecraft really is a modern marvel, especially when you consider it's built by the lowest bidders. It's the government's tight purse strings, however, that has helped open source software put its fingerprints all over the space agency.