Time is a central concept for astronomy, yet how it is communicated in educational contexts has received insufficient attention in the literature. This study explores how time-related concepts are communicated in the planetarium, by analyzing 34 different planetarium sessions held in a diversity of Portuguese institutions. Sessions were video and audio recorded. From 26 hrs of recordings, 163 excerpts related to time were identified. Studying instances of actual events with a naturalistic approach informed by ethnomethodology allowed for the identification of ordinary methods and strategies that are used by guides to teach time-related concepts. This study details these methods and strategies, and how guides take advantage of the characteristics of the planetarium. Our analysis reveals that "change over time" and "periodicity" are the most recurrent time-related themes in planetarium sessions. The majority of the excerpts relate to the rotation and revolution of the Earth, but time-related aspects of the revolution of other celestial bodies are also present in the data. We found that guides use strategies grounded both in geocentric and allocentric (view from space) perspectives when communicating about time, and we highlight how an allocentric perspective can be demonstrated without sophisticated, immersive simulations. Moreover, we found that strategies bringing time to the personal level, for instance by using birthdays and the age of members of the public as baseline measures, and other engagement techniques, are widely used. Findings have important implications for research and communication about time in practice.