An R2-D2 model in front of the Science on a Sphere exhibit at the Visitor Center at NASA's Goddard Space Flight Center in Greenbelt, Md. Star Wars cosplayers attended a "Yuri's Night" celebration at the visitor center to commemorate the first flight of cosmonaut Yuri Gagarin (April 12, 1961) and the first orbital flight of a space shuttle (April 12, 1981).