Shape of the mirrored objectAll lines of sight and lines of perspective converge at the horizon. Depending on our height we cannot see further then the visible horizon. But behind the visible horizon the lines of perspective do continu. As there is to much information aka colours behind the visible horizon there will be mirroring. Normally you will see the sky mirrored on that plane. From our point of view this mirror extends endlessly but will appear as a very small area above the visible horizon. In this mirror ships are visible for a short time, until they disappear from the bottom up due to our "mirrored" line of sight. The most interesting thing about the Sun is that it actually shows how far the mirror extends above the visible horizon. The Sun is mirrored but due to our mirrored line of sight. How this works, you can read in "calculating how long ships are visible cruising over the horizon". As the Sun is mirrored over a great distance and is cut by our line of sight, at the visible horizon it appears smaller. At the moment that the Sun sets in perspective, then it crosses our mirrored line of sight.
Dimensions of Sun and mirrored Sun
Distance to the Sun
How far is the visible horizon?So if the Sun sets it is at an approximate distance of 15650 km. Based on a eye-height of 2 m how far would actually the visible horizon be? This would result in the following distance to the visible horizon: 2/(tan(tan-1(6,35/15650)) = 4,93 km. This can also be simplified saying distance to the horizon dh=ht/0,40575 with ht is heigt eye in m and dh in km.
PS: this kind of mirroring is only posible on a flat earth model as the plane continu's and continu's as on a globe it would be blocked by the curvature of the earth.
Flat earth or hollow
Photo: Rijkswaterstaat / Harry van Reeken, https://beeldbank.rws.nl