Aldrin and the first lunar experiments, Apollo 11

Apollo 11, July 20, 1969. The whole of Tranquility Base in one frame: Aldrin looking back toward Eagle, the flag beyond, and in front of him the solar-powered seismometer he had just set up. The laser reflector the crew placed nearby is still in use, as observatories on Earth bounce lasers off it to measure the distance to the Moon. Armstrong took the photo late in a moonwalk that lasted about two and a half hours.