Most importantly, the authors argue that the current definition relegates a number of fascinating worlds to second-class status, some without proper classification. For example, Ganymede and Titan, though each larger than the planet Mercury, remain relatively forgotten amongst the general public, simply because they respectively orbit Jupiter and Saturn as moons. Meanwhile, at the edge of the solar system, the icy world Sedna defies definition.
Indeed, one could argue that the present wording is almost too solar system-centric, defining a planet based upon tired tradition and the skewed dynamics of our own cosmic neighborhood.
This leads into the best argument for the new definition. It “emphasizes a body’s intrinsic physical properties over its extrinsic orbital properties,” the authors say. While the current definition is fit for the solar system, the newly suggested version is fit for the Universe.