How far away is the horizon for the average human?

Question

I mean at sea, because otherwise there are just too many hills or valleys. I don't want answers that come from the equations where people found it to be around 3 miles, because I know that you can see a lot further than that before the curvature of the Earth. I was at Fort Niagara the other day, and looking across Lake Ontario I could see Toronto's CN Tower. I looked at an atlas later and that's approximately 30 miles away, and I could see almost the entire tower.

Here is a link to the photo I took, with the cross that's in the fort clearly in sight, and Toronto in the background, hazy but there.

http://tinypic.com/view.php?pic=23tghlz&s=4

So what's the real distance you can see before the earth curves away? (How far away is the horizon, really?)

Answer 1

It's about 20 miles.

In WWII, you could spot the tops of opposing ships'

superstructures at about 24 miles away.

Answer 2

the most of a view I could see pretty , pretty , far way

I belive That I could see straight 300 miles open no mistake

mostly of top ranges of many ,many mountain peaks,

my veiw was ALASKA .. THE LAST FRONTIER

beautiful place ..

Answer 3

Joseph and noroofoverhead numbers sound correct.   Lisa' number of 300 miles for a peak is hard to imagine.  It depends on how high up you are and how high is the object you are viewing.

I go sailing and I usually can't see the beach in a mile or two, but I can still see top of houses or trees for 7-10 miles, especially with the help of binoculars. The top of a battleship or an off-shore oil platform might be several hundred feet high. You could see those up to 20 miles away when it is clear.  You can see a 2000 feet peak about 50 miles off shore.  300 miles is a long way to see. Mount McKinley in Denali is 6200 feet tall. Even with atmospheric refraction, I doubt you could see it 200 miles off-shore.

Answer 4

http://en.wikipedia.org/wiki/Horizon

For an observer standing on the ground with h = 1.70 m (average eye-level height), the horizon appears at a distance of 4.7 km.