Lunar exploration has always held a strange position in the history of exploration. For all of human history, people have been staring up at the Moon, and for centuries astronomers used telescopes to study the lunar surface. The telescopic surveying and mapping of the Moon by astronomers can (and should, I think) be considered a form of exploration. From this perspective, the Moon had been thoroughly explored far before the dawn of the Space Age. But on the other hand, because of the nature of the Moon’s orbit, the Moon also possessed some of the most mysterious and inaccessible terrain that ever taunted exploration-minded humans.

The Moon is tidally locked, meaning that only one side of the Moon ever faces the Earth. And so for all those millennia of Moon-gazing, there was an entire half of our natural satellite that no human had ever seen before. We would only get our first look at the end of the 1950s, and it would take even longer for us to complete a full map of the Moon. Here is a visual history of how we did it, designed to guide you through the process, even if you aren’t yet familiar with any lunar features.