It is this ability to see “over the horizon”, beyond our line of sight, that can give us the illusion we live on a flat Earth. This is because the density of air decreases with height above Earth’s surface so that all light rays travelling nearly parallel to the planet’s surface bend downwards slightly, almost matching Earth’s curvature, something that surveyors take into account. Ironically, it is possible that we are able to see a ship from just as far on our spherical Earth. If the ship were as bright as a star, you might be able to see it from 13 billion light years away.īut all these conjectures are sidestepped when we factor in our atmosphere and the refraction, scattering and absorption of light that it brings.Īs the distance of the ship from us increases, so do the chances that light rays from it are refracted out of our line of sight, due to variations in air density, driven by convection. Obviously, you could see it at even greater distances with the aid of binoculars or a telescope. The maximum distance would depend on how bright it was, its size and whether you were interested in identifying it as a ship or just detecting a few photons of light.

If we were living on a flat surface without an atmosphere, the maximum distance we could see would be limited by the ability of our eyes to resolve a ship from other nearby objects and by the ship’s contrast with its background.Ī ship would be seen from the greatest distance at night if it had all its lights on.

Flat earth model