|
%I #29 Sep 10 2019 02:37:13
%S 4,1,2,5,2,9,6,1,2,4,9,4,1,9,2,7,1,0,3,1,2,9,4,6,7,1,4,6,6,1,5,5,7,2,
%T 2,6,3,9,3,3,1,9,4,0,1,7,5,9,2,6,3,1,1,5,1,5,3,9,5,3,7,5,5,8,0,0,6,6,
%U 0,4,9,9,4,6,7,9,1,5,1,7,8,9,5,3,5,7,4,9,7,6,7,7,0,1,2,7,9,9,8,7,9,8,1,4,0
%N Full solid angle of 4*Pi steradians (sr) in square degrees (degree^2).
%C "A 35 mm camera with a standard 50 mm lens covers an area some 38 degrees x 27 degrees. Theoretically, one can cover the sky with about 40 photographs." [A Field Guide]
%C One sphere = 4*Pi steradians, a spherical right angle = 1/4 hemisphere = 1/8 sphere = Pi/2 steradian.
%D John A. Adam, Mathematics in Nature, Modeling Pattern in the Natural World, Princeton University Press, Princeton & Oxford, 2003, page 78.
%D Patrick Kelly, Editor, Observer's Handbook 2007, The Royal Astronomical Society of Canada, page 32.
%D Donald H. Menzel, A Field Guide to the Stars and Planets, Houghton Mifflin Co., Boston, MA, 1964, page 317.
%H Rod Pierce, <a href="http://www.mathsisfun.com/geometry/steradian.html">MathIsFun: Steradian</a>, 2012.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SolidAngle.html">Solid Angle</a>.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Solid_angle">Solid Angle</a>.
%F 4Pi*(180/Pi)^2 = 10*A019694*A072097^2 = 129600/Pi = 129600*A049541.
%e 41252.96124941927103129467146615572263933194017592631151539537558... deg^2.
%e = 148510660.979093757126608172781606015015949846333347214554233520... min^2.
%e = 534638377792.473752565578942201378165405741944680004997239524067... sec^2.
%t RealDigits[2^6*3^4*5^2/Pi, 10, 111][[1]]
%o (PARI) 129600/Pi \\ _Charles R Greathouse IV_, Nov 06 2017
%Y Cf. A000796, A072097, A049541.
%K cons,nonn,easy
%O 5,1
%A _Robert G. Wilson v_, Dec 31 2006
%E Definition changed to make it more rigorous by _Stanislav Sykora_, Nov 14 2013
|
