http://johnnycat.wordpress.com/2010/08/02/three-triceratops-pluto/ Fri, 24 May 2013 06:04:56 +0000 hourly 1 http://wordpress.com/ http://johnnycat.wordpress.com/2010/08/02/three-triceratops-pluto/#comment-1033 Tue, 03 Aug 2010 19:49:54 +0000 http://johnnycat.wordpress.com/?p=3120#comment-1033 The “Pluto call” is just one viewpoint in an ongoing controversy and not gospel truth. Only four percent of the IAU voted on this, and most are not planetary scientists. Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. Stern and like-minded scientists favor a broader planet definition that includes any non-self-luminous spheroidal body in orbit around a star. The spherical part is important because objects become spherical when they attain a state known as hydrostatic equilibrium, meaning they are large enough for their own gravity to pull them into a round shape. This is a characteristic of planets and not of shapeless asteroids and Kuiper Belt Objects. Pluto meets this criterion and is therefore a planet. Under this definition, our solar system has 13 planets: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Haumea, Makemake, and Eris.

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