How Far Can You See?

The human eye can see an infinite distance, given that the object your viewing is large enough.

Okay I got of me arse and did some trig. I was way off last effort All numbers approximate. 400 miles = 5.8 deg  90- 5.8 = 84.2 deg  sin 84.2 = 0.995  radius of earth approx 4000 miles.  0.995 * 4000 = 3980  So there are about 20 miles in it. Been staying away from bendy light Q+A because I have been out in the Great Fuck All (guts of Australia) and seen light do some weird things, but this looks like a job for bendy stuff. 

The human eye can see an infinite distance, given that the object your viewing is large enough.

Even the flat earthers would have to admit to being able to see at least 92,955,807 miles—which is the distance to our sun.

In actuality of course we can see much further than that with the naked eye. Humans with 20/20 vision can see the star "Vega" with the naked eye.  And that's a distance of 1.5837x10¹⁴ miles.

Quote from: lolzomgz1337 on July 12, 2014, 02:18:03 PM

The human eye can see an infinite distance, given that the object your viewing is large enough.

Even the flat earthers would have to admit to being able to see at least 92,955,807 miles—which is the distance to our sun.

In actuality of course we can see much further than that with the naked eye. Humans with 20/20 vision can see the star "Vega" with the naked eye.  And that's a distance of 1.5837x10¹⁴ miles.

It all depends on what is in between you and the object you are observing.  If there is very little air, yes, you can see very far.  When you put air into the equation, though, your viewing distance is much more limited.

When you put air into the equation, though, your viewing distance is much more limited.

Nope; not over astronomical distances—such as the 1.5837x1014 miles to Vega.  The thin layer of air surrounding the earth has virtually zero impact on viewing it even with the naked eye, plus of course knowing where to look.

This is an ordinary image captured with a camera at ground level from the UK on 14 July;  no zoom lens, no telescope, and no image manipulation:




Assuming that there's no cloud cover at the time, I can only assume that you live in an extremely atmospherically polluted part of the world jroa if you can't see the constellation Lyra.

Vega has a magnitude of 0 [zero] whereas the faintest star visible to the naked human eye has a magnitude of only [plus]6.  As a guide, our full moon has a magnitude of [minus]13. 

—If you can't see Vega, then you should possibly be visiting your ophthalmologist