Based on the nature of articles about Carl Sagan, three potential things you might learn could be his contributions to popularizing science, his advocacy for space exploration, and his efforts in promoting scientific skepticism and critical thinking. These predictions are based on Carl Sagan's prominent role in the fields of astronomy, cosmology, and science communication. Considering his impact on public understanding of complex scientific concepts and his vocal support for space exploration, it is likely that the article would highlight these aspects. Additionally, Sagan's emphasis on promoting scientific skepticism and critical thinking is a recurring theme in his work, making it another probable focus of the article.