If you enjoyed playing with Stellarium, the open-source planetarium software we shared with you earlier this year, but felt strangely tied to an earth-bound perspective, you'll definitely want to fly through space with Celestia.
Celestia picks up where Stellarium leaves off. With Celestia you can zoom through the known universe, flying through star clusters and swooping in to examine far off galaxies. On its own Celestia is a really fun tool to play with but on top of the expansive star map included in Celestia there is a bustling community of astronomy hobbyists creating hundreds of add-ons for the application.
You can get add-ons for everything, from detailed maps of galaxies to extremely detailed surface maps of planets which allow you to zoom down onto the surface and get a closer look. You can even find fictional star maps and objects. In other words, if you've ever wanted to fly through the space of the Star Wars universe, this is your chance. Check out the available add-ons at The Celestia Motherlode and read up on how to use add-ons with this handy guide.
Celestia is open-source and available for Windows, Mac and Linux operating systems. You can find a portable version for Windows here. Have some experience with Celestia? Have a favourite add-on to share? Let's hear about it in the comments.