<P> The distances d and s are nearly the same when the height of the object is negligible compared to the radius (that is, h ≪ R). </P> <P> If the observer is close to the surface of the earth, then it is valid to disregard h in the term (2R + h), and the formula becomes - </P> <Dl> <Dd> d = 2 R h . (\ displaystyle d = (\ sqrt (2Rh)) \, .) </Dd> </Dl> <Dd> d = 2 R h . (\ displaystyle d = (\ sqrt (2Rh)) \, .) </Dd>

How far out on the horizon can you see