How far is the horizon at sea level assuming perfect visibilty?

Answer 1

About 2.75 miles (assuming you're about a bit over 5 feet tall, so that your eye itself is 5 feet above the ground).

------------------------
To prove this, imagine a right triangle consisting of these three lines:
- from the horizon to the center of the earth
- from the center of the earth to your eye
- from your eye to the horizon
The first line is the earth's radius (about 4000 miles, or 4000*5280 = 21,120,000 feet). The second is that same radius plus the height of your eye (say 5 feet, for a total of 21,120,005 feet). Let the third distance be x. By the Pythagorean theorem:
.....(x^2) + (21,120,000^2) = (21,120,005^2)
.....thus (x^2) = (21,120,005^2) - (21,120,000^2)*
Pull out your calculator, and you get x^2 = 211,200,025.
So x = 14,533 feet; divide by 5280 to convert to miles; x = about 2.75 miles.

------------------------
*The right side can be simplified a bit if you recall that a^2 - b^2 = (a-b)*(a+b).
Thus (21,120,005^2) - (21,120,000^2) = (difference between the roots) * (sum of the roots)
= 5 * (sum of the roots) = roughly 5 * (2 * 21,120,000)
= 10 * 21,120,000 = 211,200,000

Answer 2

in the experience that your eye-line is really at sea element - i.e. you're as a lot as your neck in water - then you genuinely're effective horizon is as far-off because the best of the subsequent wave although, i visit assume that is not quite what you meant.. :-) if you're an accepted man or woman, status on a sea coast inclusive of your feet interior the water - at sea element - on a comfortable day... your eye good will be about 5'8" or so... and your said horizon is round 3 miles.

Answer 3

On a clear day you can see 5 miles to the horizon. At that point you will see a sailboat as hull down, or just see the mast above the water level. The answer really depends on how far off the water you are. At water level it is the miles. Up to the crows nest or other super structure it increases significantly

Answer 4

Theoreticaly at sea level there is no horizon-due to the curvature of the earth. This increases rapidly as the height of observation raises.Refer to the "Height of eye" tables in any nautical almanac.They might also be available on Google.

Answer 5

If your eye is exactly at sea level, and so is the surface (land or water) around you, then no distance at all because you can only look straight down or at a tangent to the sphere of the earth. Or up, of course.

At a typical height of, say, 5 feet 8 then about 3 miles.

Answer 6

dont pick K's answer it is wrong cause it doesnt factor curve of the earth.

the truth is line of sight is typically 15 - 20 miles on the ocean, due to air tempeture, heat, air pollution, swells of the waves on the ocean etc.

but if you wanna go with one of Eiensteins mathmatical formula's of a nuclear explosion. he came up with that no matter how great
the explosion. the distance of destruction from the ground, would always be limited to about a 32.4 mile radius due the curve of the earth.

Answer 7

I concur with the approximately three mile figure for a person of average height.

Answer 8

Perfect visibility!!93, million miles!!
the setting sun? or sunrise? now there"s a shock!.

Answer 9

15 miles

Answer 10

we were always taught 15-20 miles, if you are at sea level. It rises dramatically if you go up a few feet though.