NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Arctic circle
From: Herbert Prinz
Date: 2006 Jul 5, 13:35 -0500
From: Herbert Prinz
Date: 2006 Jul 5, 13:35 -0500
Hello Robert, I understand that you are asking about linear distances. Defining the Tropics and the Arctic Circles as parallel circles at geodetic latitudes eps and 90-eps, respectively, where eps = 23.44 deg (J2000.0), and a = 6378.14, f = 1/ 298.257 (WGS 84), an approximative formula (+/- 50m) given by Andoyer (see e.g. Meeus, Astr. Alg. p.85) obtains D(Equator - Tropic) = 2593.25 km D(Pole - Arctic) = 2616.66 km For what it is worth, the geocentric latitudes of both these parallel circles are 8.4' lower than the corresponding geodetic ones (give or take 1"). This follows from phi - phi' = 692.73" sin (2 phi) - 1.16" sin (4 phi) (see Meeus, Astr. Alg. p.83). discarding the 2nd term. I can run the computation for different parameters, if you wish. Best regards Herbert Prinz Gent van R.H. wrote: >Hi, > >On a truely spherical earth the distance between the North Pole and the >Arctic Circle is equal to that between the Tropic of Cancer and the equator. > >In reality both distances should be slightly different due to the flattening >of the Earth. > >Does anyone know the exact numbers, based on current estimates for the >earth's diameter and flattening? > >Thanks in advance, > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---