Mass media have long provided general publics with science news. New media like Twitter have entered this system and provide an additional platform for the dissemination of science information. Based on automated collection and analysis of more than 900 news articles and 70,000 tweets, this study explores the online communication of current science news. Topic modeling (latent Dirichlet allocation) was used to extract five broad themes of science reporting: space missions, the US government shutdown, cancer research, Nobel Prizes and climate change. Using content and network analysis, Twitter was found to extend public science communication by providing additional voices and contextualizations of science issues. It serves a recommender role by linking to web resources, by connecting users, and by directing users’ attention. The paper suggests that microblogging adds a new and relevant layer to the public communication of science.