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Thursday, 18 August 2011

8 of 29 - Thiruvathirai (Ardra)

6.                 Why do we have “Lunar” calendar when Jupiter and Saturn are bigger than moon?

Answer: With a simple view of Newton’s theory of Gravity, the force of pull is directly proportion to the sizes, but it is also inversely proportional to the square of the distance between two objects.  Hence the farther objects like Jupiter & Saturn, even though they are heavier have lot less influence due to their distance.

As mentioned to an earlier question, a father, a mother, a teacher or a role model (friend) who is close by has a big effect compared to others who are not nearby (like the effect of an officer of a ministry or some arbitrary company’s project's manager)!

Let us consider another aspect.  The moon is approximately at a distance of 108 times its diameter.  The sun is approximately at a distance of 108 times its diameter.  That is the reason that we have total solar eclipse most of the times.  At times, when sun is nearer (earth is at perihelion and sun appears a bit bigger) & moon is farther than average (moon is at apogee and appears a bit smaller), then we have “annular” eclipse (ring of sun seen around moon).

Jupiter is at a distance much more than 108 times its diameter – hence it looks so small (otherwise it would also look the size of the sun / moon).  Obviously this leads to the conclusion that it has less effect compared to sun / moon!  Hence, a “Jupiter” based calendar makes less sense (at least to me).

(8 of 29 Thirvathirai / Ardra)

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