You start by entering a tag, and the related galaxy appears on screen. Each planet contains the pictures of a certain tag and it's size is based on the number of pictures in each category. When you click on each planet, the images are placed on a 3D rotating globe.
Here is the search I did for Disney (click on pic to see a larger image)
And then here are the pics that I got after clicking on one of the planets.
This site is absolutely amazing!