Originally Posted by

**stevek** Hi all,

Hoping that someone can come up with a simple explanation or solution to my problem ... yes, I have Googled extensively and haven't come across anything that helps.

Basically, I'm looking for a way to calculate the TOTAL height of an object that includes the height component that can be seen above your personal horizon PLUS the height component that cannot be seen because it lies below your personal horizon.

Picture a very high tower that is located 100's of kilometres away. Naturally the base of the tower and a percentage of it's total height will not be visible to you because of the Earth's curvature. Obviously it's trivial to measure the height component that you can see above the horizon ... but how do you calculate the height component that lies below the horizon ?

Thanks in advance to all those who may be able to shed some light on this.