While it is possible to select a planetary body using a touch-and-hold gesture on its label or the body itself, finding the planet can be tricky. At the very least the orbital lines and labels need to be visible. A bigger problem, however is that the "inner" and "outer" planet orbits have markedly different scales. Hence when in orbit around an outer planet it will not generally be possible to resolve an inner planet for touch-and-hold.
I therefore added a further control for selecting a planet, as shown below in Figure 1. Since moons are relatively close to a planet in comparion to other planets, touch-and-hold can be used to move to a moon in orbit around the currently selected planet. The control can be added from the tag selection bar, as shown below in Figure 1. Touching a planet switches the camera to orbit mode around the body.
The planet names and images are built at run time to ensure that they reflect any extensions to the base data.