How many miles away is the horizon?

Answer 1

It all depends on how high you are.

From Wikipedia.

• For an observer standing on the ground with h = 1.70 metres (5 ft 7 in) (average eye-level height), the horizon is at a distance of 5.0 kilometres (3.1 mi).
• For an observer standing on a hill or tower of 100 metres (330 ft) in height, the horizon is at a distance of 39 kilometres (24 mi).
• For an observer standing at the top of the Burj Khalifa (828 metres (2,717 ft) in height), the horizon is at a distance of 111 kilometres (69 mi).

Answer 2

When looking straight out say at a ship receding from a harbor with normal vision you would loose sight of the ship about 13 miles from the harbor. This is where the curvature of the earth would drop it off of the straight line of sight.

Answer 3

You certainly must be aware that the distance depends on your height above the

ground. If you want to see farther, you climb a tree or look out of an upstairs window.

The distance also depends on the atmospheric conditions, and the shape of the terrain

in the direction you're looking.

If we ignore those unpredictable factors, and consider the earth to be a simple

sphere, then we can give you the following rules from geometry only:

In metric units:

(Distance)km = 3.57 times sqrt(h) . . . 'h' is your height above ground, in meters

In imperial "customary" units:

(Distance)miles = sqrt(1.5 h) . . . 'h' is your height above ground, in feet