a simple calculation for earth spin projected onto sun-earth orbit plane.

( — written about 3 weeks ago, from 6th November 2011 )

My friend on f-b asked me how to show that “Earth rotates around sun in a tilt of 23.5 degrees and rotates around itself with spin S should mean earth-spin S is 84% along sun’s vertical and 16% along sun’s horizontal“;

I searched on Google for a trigonometric calculator and a square root calculator as linked below.

USE the following for quick calculations;

Trigonometric Definitions.

Trigonometry Calculator solves for all 6 trigonometric functions and for all 6 trigonometric arc-functions, the double line display works with degrees and radians simultaneously; sine, cosine, tangent, cotangent, secant, co-secant, arc-sine, arc-cosine, arc-tangent, arc-cotangent, arc-secant, arc-co-secant … ”

Here is the earth-around-sun and earth-spin situation:

Earth rotates around sun in a tilt of 23.5 degrees and earth rotates around itself with spin S. SO S is 84% along sun’s vertical and 16% along sun’s horizontal;


cos (square) (23.5 deg) + cos (square) (90-23.5 deg) = 1. ( — basic trigonometry )

So S_z = S.cos ( 23.5 deg ), S_xy = S.sin ( 23.5 deg ), ( — components of the spin vector of earth )

z: cos (square) ( 23.5 deg ) = ( 0.91706 )(square) = 84.09 %, xy: sin (square) ( 23.5 deg ) = ( 0.39875 ) (square)  = 15.9 %.

I am an experimental particle physicist, traveler, teacher, researcher, scientist and communicator of ideas. I am a quarkist and a bit quirky ! Hypothesis non fingo, eppur si muove, dubito cogito ergo sum are things that turn me on ! Researcher in experimental high energy physics (aka elementary particle physics; like “quarks, leptons & mesons and baryons”) … Teacher of Physics (and occasionally chemistry and maths) Blogger (check my website; mdashf.org) ! Love to read read and read but only stuff that interest me. Love to puff away my time in frivolities, just dreaming and may be thinking. Right now desperately trying to streamline myself.

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