Workshop: Create a virtual planetarium with Google Sky

Google Sky is an add-on for Google Earth, the free program that provided a 3D map of the world.

Using a similar interface and the same overlay approach, Google Sky opens up the universe to the casual stargazer, the curious amateur astronomer or the student who needs to complete a homework project.

The program requires the viewer to imagine themselves in three-dimensional space, surrounded by the rest of the mapped universe (or at least the bits that Google Sky knows about).

It tries to add realism courtesy of extravagant ­ and dizzying ­ navigational twists and turns as it moves from one celestial object to the next.

Here's how to set up Google Sky on your PC.