NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: horizon visibility puzzle
From: Aubrey O´Callaghan
Date: 2001 Jun 20, 2:28 PM
From: Aubrey O´Callaghan
Date: 2001 Jun 20, 2:28 PM
Basically this is a distance to horizon problem: On the 777 m hill you can see: 1.144 sqrt( 777*3.281) = 57.76 n. miles On the 401 m hill you can see 1.144sqrt(401*3.281)= 41.5 n miles now hills are 35 km apart 35/1.8=19.44 n. miles If 777 and 401 m hill were at same place the difference in distance viewed would be 16.26 n miles If we move 401 m hill forward 16.26 n miles we can both see the same point. Therefore this is the line cutting both top of both hills to horizon. But we have moved it forward 19.44 n .miles so 401 hill will block 777 hill. We cannot see the ocean from 777 hill due to presence of 401 hill. Aubrey. At 03:17 PM 20-06-01, you wrote: >You are ashore, 777 meters above sea level, looking toward the ocean. >In your line of sight, 35 kilometers away, is a hill 401 meters high. >Can you see the ocean over the top of this hill? > >This is an actual question someone has asked. I've come up with an >answer, but am curious how others might solve the problem. One person >approached it from a completely different direction than I used but >got the same answer. > >-- > > >paulhirose@earthlink.net (Paul Hirose)