A mockup of the Apollo Guidance Computer that navigated Apollo’s way to the Moon. MIT Library.

Driving, say, to a friend’s house, we usually have directions to follow like “turn left at the light then it’s the third door on the right.” The same isn’t true when going to the Moon; there are no signposts guiding the way. So how exactly did Apollo astronauts know where they were going when they went to the Moon?

This one is tough. You can’t just launch a rocket towards the Moon and expect