<Dl> <Dd> s = R tan − 1 ⁡ d R . (\ displaystyle s = R \ tan ^ (- 1) (\ frac (d) (R)) \, .) </Dd> </Dl> <Dd> s = R tan − 1 ⁡ d R . (\ displaystyle s = R \ tan ^ (- 1) (\ frac (d) (R)) \, .) </Dd> <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>

How many miles can you see until the earth curves