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Saddam Hussein was killed, Google bought YouTube for $ 1.65 billion, and Pluto was downgraded to a "dwarf planet," a new classification created by the International Astronomical Union (IAU). controversial reclassification, Pluto 's status argument has arisen repeatedly, with polls as recent as 2014 showing that popular opinion is that Pluto should never have lost its planet status, by CNN.
Philip Metzger, global scientist at the University of Central Florida, agrees. He is the principal author of a study published in the journal Icarus arguing that the initial reclassification was invalid because of the inclusion of an arbitrary criterion in the definition of "planet". When IAU updated the definition of a planet, it chose the following:
(1) A planet is a celestial body
(a) is in orbit around the sun,
(b) has sufficient mass for self-gravity to overcome rigid body forces
so that it adopts a form of hydrostatic equilibrium (almost round),
and (c) cleared the neighborhood around its orbit.
This is the last part that caused problems to Pluto. Due to the small size of Pluto, it is impossible to "clear the neighborhood" as do large planets like Jupiter, the Earth or even Mars. A cursory examination of the surface of Pluto shows very few craters, unlike the surfaces of other rocky planets and moons, indicating that it does not encounter much random space debris. It is also important to note that with Pluto as distant as it is, there is not much to eliminate in the neighborhood, so it makes sense that there are not so many craters.
Metzger argues that the third criterion should not be applied because it is not a concept used in scientific research. It is also subjective; How does one define the cleaning of the neighborhood? He has support in his concerns. according to Fox News, Owen Gingerich of Harvard, who was the president of AIU in 2006 when Pluto was demoted, said National Geographic something similar in 2014.
I thought it was really stupid that the AIU had taken as a "dwarf planet" category and then said, "But these are not planets." I was disappointed that this happened .
If given the choice, Metzger would like the appearance of the neighborhood to be removed and the determination for a planet to be whether its gravity is sufficient to keep it in a spherical shape, similar to the article ( b) the current definition. He points out that the ability to do this is an important step in the evolution of a planetary body, because it is the point where pressures become intense enough to initiate an "active geology in the body".
IAU noted that there is a way forward to resolve the problem, through a motion to the group's governing body to propose a new resolution, but so far nobody has gone through this process.
Pluto is definitely a planet, say some scientists who say it should never have been downgraded https://t.co/luI4DbxdL9 pic.twitter.com/9oauTdJRpU
– CNN (@CNN) September 16, 2018
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