Can Apollo 11 be seen from Earth?

At the landing site the Eagle's descent stage remains — the lower half of the lunar module that served as a launch platform for Armstrong and Aldrin. It's still there, intact, but no ground-based telescope can make it out: at that distance, an object a few meters across falls well below what any Earth-based instrument can resolve. Visual proof had to come from much closer.

NASA's Lunar Reconnaissance Orbiter (LRO) photographed the site decades after the landing. Its images show the descent stage, as well as the tracks left by the astronauts' boots on the regolith, visible because the disturbed dust reflects light differently than undisturbed ground.

There is, however, a way to reach Apollo 11 from Earth: the laser reflector the crew deployed on July 21, 1969. It's a square panel, 46 by 46 centimeters, containing 100 corner-cube prisms, a design that sends light back exactly in the direction it came from. A telescope fires a laser pulse, the panel reflects it, and the round-trip time is measured.

More than fifty years later it still provides first-rate scientific data: the Earth-Moon distance with enormous precision, its slow and steady increase, our planet's orientation, and properties of the lunar interior. It's the Apollo program experiment that never switched off.

The only piece of Apollo 11 that can be seen up close is on Earth: the Columbia command module, the part of the spacecraft that returned with the three crew members, is held in the collection of the Smithsonian's National Air and Space Museum.