Discover three December 15 science milestones: the Soviet Venera 7 probe transmits data from Venus, Henri Becquerel’s work leads to the discovery of radioactivity, and NASA’s Gemini 6A and 7 achieve the first rendezvous between crewed spacecraft. Explore science history with 132 December events in an interactive HTML resource, editable slides, spreadsheet and printable PDF for middle and high school classrooms.