After years of debate about Pluto’s status as a planet, hundreds of the world’s most prominent astronomers voted to totally redefine what classifies a planet.  And guess what? Pluto no longer qualifies.  Now, Pluto has a lowly position as a dwarf planet. Millions of textbooks will have to be re-written and toys galore are now outdated with this declassification.

The whole rigmarole about what to define the now former planet Pluto started once scientists and astronomers recognized that it was littler than it appeared when first encountered in 1930.  Back then, Pluto was thought to be large enough to mess with the orbits of Uranus and Neptune.  Years later, this hypothesis was chalked up to human error.

Over the years, scientists have always believed that there was something distinct and solid about our remaining eight planets in the solar system – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. However, until recently, there was no real classification of what a planet constituted. It was a matter of that principle of “knowing it when we see it.”

The first alternative would be to name any object that was orbiting the sun and that was bigger than a predetermined size would be a planet.  Of course, if the minimum measurement were small enough, it would encompass Pluto and be back to planet status.  Then again, if this minimum measurement scenario were incorporated, it would include another hunk of rock dubbed Xena, which is further out than Pluto and bigger to boot.

Another option would be to define a planet as any orbiting thing that is big enough to have gravity form it into a round shape.  If this was the definition then not only would our recently dismissed Pluto make the cut but also Xena and another object called Ceres, which makes an orbit between Jupiter and Mars.

With the vote from hundreds of astronomers around the world, the definition for planet became to be generally defined as an object that dominated their own orbits but also taking smaller things before them. That general description knocked Pluto out of the solar system running for planet status. 

Pluto is now considered a dwarf planet.  A dwarf planet can be defined as a celestial mass that is in orbit around the Sun in our solar system.  In addition, a dwarf planet can also be defined as having sufficient weight to create its own gravity while conquering unyielding powerful forces that mold its shape into a round format. Another aspect to dwarf planets is that they are not satellites (an object that orbits a mass larger than itself) nor have they totally followed a complete orbital path.

Some of the classifications of what makes a dwarf planet are what disqualified Pluto from planet status.  For instance, Pluto does not have a round orbit.  Rather is it oblong-shaped and gets into Neptune’s territory.  There are some naysayers in the astronomy community that think that Pluto should remain a planet.  However, a large contingent of the same community says that most of the controversy stems not from the reclassification but discovering what you’ve always learned is no longer.

With better tools in which to gaze upon the heavens, it is no wonder that there is some definition shuffling in the astronomy community.  It stands to reason that everyone is going to discover new things that are bound to challenge the tradition thinking of the community and even the public in general.  And many believe that is what has happened with the demotion of Pluto to a dwarf planet. As one scientist has said, “Progress is simply the growing pains of an existing theory.”

Photo Credit:  Eliot Young (SwRI) et al., NASA

Source:  http://antwrp.gsfc.nasa.gov/apod/ap010319.html

Explanation: Pluto is mostly brownish-green. The above picture captures the true colors of Pluto as well as the highest surface resolution so far recovered. No spacecraft has yet visited this dwarf planet in our Solar System. The above map was created by tracking brightness changes from Earth of Pluto during times when it was being partially eclipsed by its moon Charon. The map therefore shows the hemisphere of Pluto that faces Charon. Pluto’s brownish-green color is thought dominated by frozen methane deposits metamorphosed by faint but energetic sunlight. The dark band below Pluto’s equator is seen to have rather complex coloring, however, indicating that some unknown mechanisms may have affected Pluto’s surface.

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