2007-02-19 23:44:59 · 8 answers · asked by jamall69 2 in Science & Mathematics ➔ Biology
Well I have considerably less than 20:20 vision and I can see stars that are thousands of light-years away.
Wow...either I have superhuman powers or your question is meaningless.
2007-02-20 00:11:33 · answer #1 · answered by gebobs 6 · 0⤊ 0⤋
Thousands of light years - because they could see stars, couldnt they?
Obvious how far the eyes could reach doesn't even make any sense and it seems to imply a misunderstanding about how eyes work.
What you're after is the resolving power.
A human with normal (misleading to call it perfect) 20/20 vision could resolve about a minute of arc - some people have up to 20/12 vision.
2007-02-20 00:30:04 · answer #2 · answered by Leviathan 6 · 1⤊ 0⤋
the resolution of the eye is not given as the distance a object of a certain size can be seen, but as angular resolution. This makes the value independent of distance.
The resolution of your eye depends also how bright it is, but during the day for a person with 20/20 vision it is about 1 arc minute (an arc minute is 1/60th of a degree). So as long as an object is 1 arc minute large in your field of vision you can see it, regardless if it is light years away or close to the tip of your nose.
2007-02-20 00:34:57 · answer #3 · answered by eintigerchen 4 · 2⤊ 0⤋
Some people have better vision. It is said that the veteran British racing driver Sir Stirling Moss, as a young man in the 1950s could read a newspaper from across a room in average lighting.
2007-02-19 23:50:59 · answer #4 · answered by Anonymous · 1⤊ 0⤋
in a normal health human eye , the near point for clear sight(without straining the eyes) is 25cm and far point for vision is infinity.
2007-02-19 23:47:45 · answer #5 · answered by ssuasw 3 · 2⤊ 0⤋
Approximatley 3 feet
2007-02-19 23:47:09 · answer #6 · answered by Joe K 2 · 0⤊ 3⤋
20 feet
2007-02-20 01:50:40 · answer #7 · answered by Suzy-Q 1 · 0⤊ 1⤋
Until obstructed you can see as far as possible.For example as we look at ocean or the sky its so far away
2007-02-19 23:50:48 · answer #8 · answered by kalabalu 5 · 1⤊ 0⤋