Proposed Radically Different New Definition of 'Planet'

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Yazata, Feb 22, 2017.

  1. Yazata Valued Senior Member

    We are all aware that Pluto was demoted from 'planet' to 'dwarf planet' years ago.

    Well, Pluto's planet status might be restored, if a new proposal is adopted by the International Astronomical Union (which decides on such things).

    The new definition of 'planet' would not only restore Pluto, it would acknowledge some 100 new planets in our solar system, including the earth's moon!

    The idea is that planets should be defined by their own physical properties, their geophysics as it were, rather than by their orbital characteristics. So a 'planet' would become a matter of what kind of body it is, not what kind of orbit it has. If this proposal is adopted, it will no longer be necessary that the objects orbit a star. Objects (moons) orbiting larger planets would count as planets too, if they have enough gravity to form into spheres but are not massive enough to initiate fusion. (Would brown dwarfs be included in that?) It would also make room in the planet definition for 'rogue planets' that probably exist in the darkness of interstellar space not associated with any particular star.
    Last edited: Feb 22, 2017

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