how far can the eye see

ynp205moon

How far can the human eye see?

Think about it.

What’s the answer?
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I saw this on an r/askreddit thread that asked: “What’s the smartest thing you’ve ever done?”

seeingmoonreddit

Duh.

Probably further, because some stars are way, way past the moon. The andromeda galaxy, located 2.6 million light years away, is the furthest object visible with the naked eye under the right conditions.

Those military higher-ups were probably asking how far can the human eye see on earth and with the ability to see details. Or the more common question, how far can a human eye detect a candle flame? The quickest answer from googling is 48km. Researchers at Texas A&M university say it’s less than that, at around 2.5-2.8 km.

It’s surprisingly hard to test, because there are assumptions and external variables. Do we take into account the earth’s curvature? At around 3km it’s less significant than 48km. How about light pollution? Even in completely rural areas, are we seeing the candle flame absent light from the stars and the moon? How about under conditions of absolute darkness?

I can see why there was a discussion.