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Comment by nonrandomstring | Hacker News Reader

The "Cat's Eye" reflector used on roads was invented by Percy Shaw [1] in the 1930s. It's arguably saved miliions of lives and is found all around the world. It is a design that's simple, passive, robust, cheap and very effective, making it one of the all-time great inventions

[1] Richard Hollins Murray contributed to the idea

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It also has the distinction of being the cheapest way that anyone can verify that human artifacts are on the Moon, by bouncing a laser off one of several retroreflectors left behind by the Apollo missions.

You can't quite prove from there that humans were down there as well, but let's say it pushes the balance of evidence in the right direction.

There's a convincing chain of evidence that the retroreflectors were placed by humans, but while I can probably verify there are good reflectors there now, I can't verify there weren't good reflectors there before the mission. I didn't have access to lasers back then, when they were quite expensive and I wasn't alive.

Alright, granted: there is at least one sheep in Scotland, which is black at least on one side.

You could record where the reflectors are and how many you observe today. Then, assuming your progeny hold sufficient trust in you and your memory, your children would be able to compare your notes with their future notes, by which time NASA will have placed additional retroreflectors on the moon. The difference would be proof that we've been to the moon.

The lunar reflectors are corner cubes. The original cats eye reflectors were glass spheres.

Richard Hollins Murray is somewhere in my ancestry (Murray is a family name), probably a very distant relative. God forbid someone mentions the cat's eye at a family party, though, because all of the great-aunts and great-uncles get up in arms about how Murray's idea was "stolen" and how Murray was the true inventor of the cat's eye. I don't think any of them really know the history (I didn't know his name was Richard before I saw his this post) but I'm not going to argue with a gang of riled-up octogenearians.

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