The theme of this work is the practice of science communication (CD) in science and technology museums, more specifically in the Museum of Astronomy and Related Sciences - MAST (Brazil / Rio de Janeiro). We sought to analyse how this practice takes place in the exhibitions of the chosen museum by means of a theoretical and empirical analysis of the chosen exhibitions. The reason for this is that I am a museologist, because of the museum's importance in the museal and educational spheres and because we have investigated patterns of DC in the exhibitions. The predominant methodology was the study of literature pertinent to the subject: articles, books and texts were consulted to construct the dissertation, as well as official documents to understand the creation of MAST and the exhibitions chosen. We also visited the museum in order to observe the space in situ and photograph the current exhibitions. The material collected was analysed using content analysis. The conclusion of the research is that the DC actions present in the museum in question differ from exhibition to exhibition and from time to time according to their purpose.