The domain of astronomy contributes a wealth of knowledge to the corpus of any general encyclopedia. Modern multimedia encyclopedias are capable of displaying complex, three-dimensional visualizations in real-time, enabling the integration of a planetarium, a virtual theater presenting astronomical facts in an educational and entertaining way. The manifold peculiarities of astronomical data sets require careful balancing of visual means to create representations comprehensible for a general audience. In this paper we discuss design and implementation considerations for a Planetarium integrated with the prevalent German language multimedia encyclopedia.