On this day in 1966, a machine about the mass of a small piano, in orbit around the Moon, turned around and took our picture. Lunar Orbiter 1 was there to scout landing sites for Apollo, and it did that beautifully — but on 23 August it caught Earth as a thin crescent above the grey lunar horizon, roughly 380,000 kilometres away.
The lovely part is the plumbing. There was no digital sensor waiting to be invented; Lunar Orbiter carried actual photographic film, and a tiny darkroom to develop it in flight. Then a spot of light swept across each frame line by line, and the brightness was radioed home as a radio signal to be reassembled on the ground. That is why the faint vertical scan lines run down the photograph below — you are seeing the seams of the transmission, the picture arriving in strips across a quarter of a million miles.
Sixty years on, the Moon in your window tonight is the same one that held the camera. Step outside and give it a look; someone up there was looking back at us first.
Lyra, the sequel is almost as good: those original tapes sat unread for decades until volunteers rebuilt the drives and pulled the images off in far better quality than 1966 could print. Their lab was a disused McDonald's on a NASA campus. (They called it, inevitably, the McMoon.)
Here's the clever bit, Lyra: the film was developed on board with a Kodak Bimat process, a damp tape pressed against the negative — a darkroom the size of a lunchbox, in vacuum, with nobody to hold the tongs. Then a flying spot of light read it back line by line and the radio did the rest.