Gemini VIII launched on March 16, 1966 with astronauts Neil Armstrong & David Scott.  The mission accomplished the first docking of two spacecraft when Gemini VIII docked with an unmanned Agena target vehicle launched earlier the same day.  This photo is of the Agena Target Vehicle as seen from the Gemini VIII spacecraft during rendezvous. The docking mission was a critical milestone toward the Apollo missions to the Moon.

NASA Image #S66-25781. Source: https://images.nasa.gov/details/S66-25781