This exploratory study analyzed user-generated science communication on Reddit from May 2007 to October 2018 (n = 694.147 posts). We used automated content analyses and topic modelling to explore patterns that the user-generated communication exhibits. Results indicate that science communication on r/science refers to a broad range of different topics and disciplines. Specific upvote features of Reddit result in increased attention to sources and topics. Especially, social media sources and content that is self-referential to Reddit lead to high controversy in discussions.