In this paper we suggest the ceiling as a new physical surface for information visualization. To provide a design framework for application designers, we present the notion of `information sky´. This concept is based on (1) the metaphor of the natural sky, (2) historical examples of ceiling art and (3) recent computing paradigms, including mediatecture, ubiquitous computing and ambient display. We further introduce three distinct categories that denote potential application domains for ceiling-based data visualizations. Finally, we present four different application scenarios we have developed using prototyping and user-centered design techniques, and discuss how they relate to the categories.