In the latest video of his series Things You Might Not Know, Tom Scott shows us something you most likely have never heard of -unless you pilot boats into a harbor. There are lights that use the moiré effect to steer ships into the right path, no matter where the ship is at the time the sign is spotted. And what's more fascinating was Scott's search into where they came from.
If there's one thing I am very familiar with, it's how a typo can totally screw up an internet search. Now that you've learned about them, you can tell your buddies about Inogon leading marks, and they might even believe you, but I wouldn't count on it. -via