back to article How far can the naked eye see?

Also in this week's column: What is Alice in Wonderland syndrome? Can you really see the Great Wall of China from the Moon? Are secretive people more or less healthy? How far can the naked eye see? The human eye can see an almost unlimited distance. Looking up into the sky on a very clear night, the Triangulum Galaxy can …

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Err...yeah

"However, it must be pointed out that when we see these galaxies what we actually "see" is something at a somewhat lesser distance. What we "see" is light from the far away object rather than the object itself."

Uhh...ya think? And how exactly do we see closer objects?? Do they physically jump inside of your eyeball and push on your brain? That's great of them to point out that when we see far away objects, we are in fact seeing light...thanks for the much needed clarification.

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Anonymous Coward

Seeing the light?

Waitaminute: 'What we "see" is light from the far away object rather than the object itself.'

Isn't that how the human "eye" works? I mean, is there an instance where you see the "object" instead of the light coming from (reflecting off) it?

I think a better answer would be this:

The human eye has no limitations on distance. Since the eye is a device that detects and interprets light, the only limitation is the distance that light is capable of traveling, not a limitation to the eye itself.

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Anonymous Coward

What about the angle of vision

A more interesting question would be the smallest angle at which the eye can distinguish two objects. Expressed differently, what is the resolution of the retina or how many dots/polygons can the eye distinguish.

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M81.

I've seen a couple of claims that under ideal (dark sky, dry air and high altitude) conditions, M81 (IIRC) at a distance of 12,000,000 lightyears can be glimpsed using averted vision. (If not M81, then another of the Messier objects

But claiming distance records for viewing galaxies is kind of cheating, since what we are seeing there is the aggregate light of hundreds of billions of stars.

A more accurate measure of the acuity of the human eye, would be the furthest individual object visible to the unaided eye. Which for most folk now living would have been SN1987A.

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distance

Seems to me that the question "how far can the eye see" implies some sort of active process where the eye has to reach out in some manner in order to perceive. However, it seems more accurate to say that the eye is a passive receiver. Thus the real question is "how far can a photon travel?"

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Anonymous Coward

ORLY

"However, it must be pointed out that when we see these galaxies what we actually "see" is something at a somewhat lesser distance. What we "see" is light from the far away object rather than the object itself."

Er - All we EVER see is reflected light! and our Stereoscopic vision allows us judge distance.

We never actually see 'objects' per se.

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