Saturday, August 26, 2006

Redefining A Planet

Some of you might have heard the news, our solar system has been formally diminished by one planet!! Its no longer a 9-planet system, but an 8-planet one... Pluto was omitted from the planets' definition! This incidence reminds us of the utmost importance of definitions as the slightest change in the wording of a definition might include or exclude stuff from the set of things that a word describes!! It can be easily noted that imprecise definition cause most of the disagreements and misunderstandings...

I always like to provide the "prime numbers" definition example: Is 1 a prime number? Short answer: NO! But why? The answer to this question comes from the definition of a prime number: A prime number is a positive integer that is divisible (integer division without remainder) by exactly two different positive integers: 1 and itself only!! Considering one, one is divisible by one and also divisible by itself... The problem is one and itself are not "different"!!

Numerous other examples can be given so let's remember: Definitions make the difference between hell and heaven!! Definitions are the ultimate references for any concrete argument... Enough said!!

Back to the planets issue: Apparently scientists made few discoveries about bodies that goes around the sun; Bodies which are comparable to Pluto in terms of size and orbit, led to a situation where either the minor bodies would be added the list of officially recognized planets, or older ones would need to be removed, in order to ensure consistency of definition. The definition for planet is now officially "a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape and (c) has cleared the neighborhood around its orbit." Pluto fails to satisfy condition (c) and therefore here we are now: One less planet we have!

Sources: wikipedia,

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